From R to CFF

Crosswalk

Diego Hernangómez

This vignette provides an explicit map between the metadata sources used by cffr and each valid key in the Citation File Format schema version 1.2.0.

Summary

This section summarizes the keys that cffr can coerce and the source of information for each one. Details for each key are presented in the next section. The assessment is based on the Guide to Citation File Format schema version 1.2.0 (Druskat et al. 2021).

key source
abstract DESCRIPTION file
authors DESCRIPTION file
cff-version function argument
commit DESCRIPTION file
contact DESCRIPTION file
date-released DESCRIPTION file
doi inst/CITATION
identifiers DESCRIPTION and inst/CITATION
keywords DESCRIPTION file
license DESCRIPTION file
license-url Ignored by cffr
message DESCRIPTION file
preferred-citation inst/CITATION
references DESCRIPTION and inst/CITATION
repository DESCRIPTION file
repository-artifact Ignored by cffr
repository-code DESCRIPTION file
title DESCRIPTION file
type Fixed value: ‘software’
url DESCRIPTION file
version DESCRIPTION file
Table 1: cffr and R packages: Conversion table

Details

abstract

This key is extracted from the "Description" field of the DESCRIPTION file.

Example 
library(cffr)

# Create a `cff` object for YAML.

cff_obj <- cff_create("rmarkdown")

# Get the DESCRIPTION of **rmarkdown** to check.

pkg <- desc::desc(file.path(find.package("rmarkdown"), "DESCRIPTION"))

cat(cff_obj$abstract)
#> Convert R Markdown documents into a variety of formats.

cat(pkg$get("Description"))
#> Convert R Markdown documents into a variety of formats.

Back to Table 1.

authors

This key is coerced from the "Authors" or "Authors@R" field of the DESCRIPTION file. By default, persons with the role "aut" or "cre" are considered, but this can be modified with the authors_roles argument.

Example 
# An example DESCRIPTION.
path <- system.file("examples/DESCRIPTION_many_persons", package = "cffr")
pkg <- desc::desc(path)

# See the listed persons.
pkg$get_authors()
#> [1] "Diego Hernangómez <fake@gmail.com> [aut, cre] (ORCID: <https://orcid.org/0000-0001-8457-4658>, email: error, not-valid: error)"
#> [2] "Joe Doe <I am a wrong email> [aut] (affiliation: This One, country: ES, date-end: error)"                                      
#> [3] "Pepe Doe <fake@gmail.com> [aut] (error)"                                                                                       
#> [4] "I am an entity [cre] (date-end: 2020-01-01, affiliation: error)"                                                               
#> [5] "ERROR entity [cph] (for the administrative boundaries.)"                                                                       
#> [6] "ERROR person [cph] (ORCID: <https://orcid.org/0000-0003-2042-7063>, for the gisco_countrycode dataset.)"

# Default behavior: use authors and creators (maintainers).
cff_obj <- cff_create(path)
cff_obj$authors
#> - family-names: Hernangómez
#>   given-names: Diego
#>   email: fake@gmail.com
#>   orcid: https://orcid.org/0000-0001-8457-4658
#> - family-names: Doe
#>   given-names: Joe
#>   affiliation: This One
#>   country: ES
#> - family-names: Doe
#>   given-names: Pepe
#>   email: fake@gmail.com
#> - name: I am an entity
#>   date-end: '2020-01-01'

# Use copyright holders and maintainers.
cff_obj_alt <- cff_create(path, authors_roles = c("cre", "cph"))
cff_obj_alt$authors
#> - family-names: Hernangómez
#>   given-names: Diego
#>   email: fake@gmail.com
#>   orcid: https://orcid.org/0000-0001-8457-4658
#> - name: I am an entity
#>   date-end: '2020-01-01'
#> - name: ERROR entity
#> - family-names: person
#>   given-names: ERROR
#>   orcid: https://orcid.org/0000-0003-2042-7063

Back to Table 1.

cff-version

This key can be set with the arguments of the cff_create()/cff_write() functions:

Example 
cff_objv110 <- cff_create("jsonlite", cff_version = "v1.1.0")

cat(cff_objv110$`cff-version`)
#> v1.1.0

Back to Table 1.

commit

This key is extracted from the "RemoteSha" field of the DESCRIPTION file. This is the case of packages installed using the r-universe or packages such as remotes or pak.

Example 
# An example DESCRIPTION.
path <- system.file("examples/DESCRIPTION_r_universe", package = "cffr")
pkg <- desc::desc(path)

# See `RemoteSha`.
pkg$get("RemoteSha")
#>                                  RemoteSha 
#> "bdd9a29d7eabcc43c3195fe461f884932eba763c"

cff_read(path)
#> cff-version: 1.2.0
#> message: 'To cite package "codemetar" in publications use:'
#> type: software
#> title: 'codemetar: Generate ''CodeMeta'' Metadata for R Packages'
#> version: 0.3.5
#> authors:
#> - family-names: Boettiger
#>   given-names: Carl
#>   email: cboettig@gmail.com
#>   orcid: https://orcid.org/0000-0002-1642-628X
#> - family-names: Salmon
#>   given-names: Maëlle
#>   orcid: https://orcid.org/0000-0002-2815-0399
#> abstract: The 'Codemeta' Project defines a 'JSON-LD' format for describing software
#>   metadata, as detailed at <https://codemeta.github.io>. This package provides utilities
#>   to generate, parse, and modify 'codemeta.json' files automatically for R packages,
#>   as well as tools and examples for working with 'codemeta.json' 'JSON-LD' more generally.
#> repository: https://ropensci.r-universe.dev
#> repository-code: https://github.com/ropensci/codemetar
#> url: https://docs.ropensci.org/codemetar/
#> date-released: '2024-02-09'
#> contact:
#> - family-names: Boettiger
#>   given-names: Carl
#>   email: cboettig@gmail.com
#>   orcid: https://orcid.org/0000-0002-1642-628X
#> keywords:
#> - metadata
#> - codemeta
#> - ropensci
#> - citation
#> - credit
#> - linked-data
#> - json-ld
#> - peer-reviewed
#> - r
#> - r-package
#> - rstats
#> license: GPL-3.0-only
#> commit: bdd9a29d7eabcc43c3195fe461f884932eba763c
#> doi: 10.32614/CRAN.package.codemetar

Back to Table 1.

contact

This key is coerced from the "Authors" or "Authors@R" field of the DESCRIPTION file. Only persons with the role "cre" (that is, maintainers) are considered.

Example 
cff_obj <- cff_create("rmarkdown")
pkg <- desc::desc(file.path(find.package("rmarkdown"), "DESCRIPTION"))

cff_obj$contact
#> - family-names: Xie
#>   given-names: Yihui
#>   email: xie@yihui.name
#>   orcid: https://orcid.org/0000-0003-0645-5666

pkg$get_author()
#> [1] "Yihui Xie <xie@yihui.name> [aut, cre] (ORCID: <https://orcid.org/0000-0003-0645-5666>)"

Back to Table 1.

date-released

This key is extracted from the DESCRIPTION file using this logic:

Example 
# Use an installed package.

cff_obj <- cff_create("rmarkdown")
pkg <- desc::desc(file.path(find.package("rmarkdown"), "DESCRIPTION"))

cat(pkg$get("Date/Publication"))
#> 2026-03-26 16:30:02 UTC

cat(cff_obj$`date-released`)
#> 2026-03-26

# A DESCRIPTION file without a `Date`.
nodate <- system.file("examples/DESCRIPTION_basic", package = "cffr")
tmp <- tempfile("DESCRIPTION")

# Create a temporary file.
file.copy(nodate, tmp)
#> [1] TRUE

pkgnodate <- desc::desc(tmp)
cffnodate <- cff_create(tmp)

# No value is returned.
cat(cffnodate$`date-released`)

pkgnodate
#> Type: Package
#> Package: basicdesc
#> Title: A Basic Description
#> Version: 0.1.6
#> Authors@R (parsed):
#>     * Marc Basic <marcbasic@gmail.com> [aut, cre, cph]
#> Description: A very basic description. Should parse without problems.
#> License: GPL-3
#> URL: https://github.com/basic/package, https://basic.github.io/package
#> BugReports: https://github.com/basic/package/issues
#> Encoding: UTF-8
#> LazyData: true
#> RoxygenNote: 6.0.1.9000

# Add a `Date`.

desc::desc_set("Date", "1999-01-01", file = tmp)
#> Type: Package
#> Package: basicdesc
#> Title: A Basic Description
#> Version: 0.1.6
#> Date: 1999-01-01
#> Authors@R (parsed):
#>     * Marc Basic <marcbasic@gmail.com> [aut, cre, cph]
#> Description: A very basic description. Should parse without problems.
#> License: GPL-3
#> URL: https://github.com/basic/package, https://basic.github.io/package
#> BugReports: https://github.com/basic/package/issues
#> Encoding: UTF-8
#> LazyData: true
#> RoxygenNote: 6.0.1.9000

cat(cff_create(tmp)$`date-released`)
#> 1999-01-01

Back to Table 1.

doi

This key is coerced from the "doi" field of the preferred-citation object. If not present and the package is on CRAN, it is populated with the DOI provided by CRAN (e.g. https://doi.org/10.32614/CRAN.package.cffr).

Example 
cff_doi <- cff_create("cffr")

cat(cff_doi$doi)
#> 10.21105/joss.03900

cat(cff_doi$`preferred-citation`$doi)
#> 10.21105/joss.03900

Back to Table 1.

identifiers

This key includes all the possible identifiers of the package:

Example 
file <- system.file("examples/DESCRIPTION_many_urls", package = "cffr")

pkg <- desc::desc(file)

cat(pkg$get_urls())
#> https://github.com/test/package https://test.github.io/package/ https://r-forge.r-project.org/projects/test/ http://google.ru https://gitlab.com/r-packages/behaviorchange

cat(cff_create(file)$url)
#> https://test.github.io/package/

cat(cff_create(file)$`repository-code`)
#> https://github.com/test/package

cff_create(file)$identifiers
#> - type: url
#>   value: https://r-forge.r-project.org/projects/test/
#> - type: url
#>   value: http://google.ru
#> - type: url
#>   value: https://gitlab.com/r-packages/behaviorchange

Back to Table 1.

keywords

This key is extracted from the DESCRIPTION file. The keywords should appear in the DESCRIPTION as:

...
X-schema.org-keywords: keyword1, keyword2, keyword3
Example 
# A DESCRIPTION file without keywords
nokeywords <- system.file("examples/DESCRIPTION_basic", package = "cffr")
tmp2 <- tempfile("DESCRIPTION")

# Create a temporary file.
file.copy(nokeywords, tmp2)
#> [1] TRUE

pkgnokeywords <- desc::desc(tmp2)
cffnokeywords <- cff_create(tmp2)

# No value is returned.
cat(cffnokeywords$keywords)

pkgnokeywords
#> Type: Package
#> Package: basicdesc
#> Title: A Basic Description
#> Version: 0.1.6
#> Authors@R (parsed):
#>     * Marc Basic <marcbasic@gmail.com> [aut, cre, cph]
#> Description: A very basic description. Should parse without problems.
#> License: GPL-3
#> URL: https://github.com/basic/package, https://basic.github.io/package
#> BugReports: https://github.com/basic/package/issues
#> Encoding: UTF-8
#> LazyData: true
#> RoxygenNote: 6.0.1.9000

# Add keywords.

desc::desc_set(
  "X-schema.org-keywords",
  "keyword1, keyword2, keyword3",
  file = tmp2
)
#> Type: Package
#> Package: basicdesc
#> Title: A Basic Description
#> Version: 0.1.6
#> Authors@R (parsed):
#>     * Marc Basic <marcbasic@gmail.com> [aut, cre, cph]
#> Description: A very basic description. Should parse without problems.
#> License: GPL-3
#> URL: https://github.com/basic/package, https://basic.github.io/package
#> BugReports: https://github.com/basic/package/issues
#> Encoding: UTF-8
#> LazyData: true
#> RoxygenNote: 6.0.1.9000
#> X-schema.org-keywords: keyword1, keyword2, keyword3

cat(cff_create(tmp2)$keywords)
#> keyword1 keyword2 keyword3

Additionally, if the source code of the package is hosted on GitHub, cffr can retrieve the topics of the repository with the GitHub API and include those topics as keywords. This option is controlled with the gh_keywords argument:

Example 
# Get a `cff` object from **jsonvalidate**.

jsonval <- cff_create("jsonvalidate")

# Keywords are retrieved from the GitHub repository.

jsonval
#> cff-version: 1.2.0
#> message: 'To cite package "jsonvalidate" in publications use:'
#> type: software
#> license: MIT
#> title: 'jsonvalidate: Validate ''JSON'' Schema'
#> version: 1.5.0
#> doi: 10.32614/CRAN.package.jsonvalidate
#> abstract: Uses the node library 'is-my-json-valid' or 'ajv' to validate 'JSON' against
#>   a 'JSON' schema. Drafts 04, 06 and 07 of 'JSON' schema are supported.
#> authors:
#> - family-names: FitzJohn
#>   given-names: Rich
#>   email: rich.fitzjohn@gmail.com
#> - family-names: Ashton
#>   given-names: Rob
#> - family-names: Buus
#>   given-names: Mathias
#> - family-names: Poberezkin
#>   given-names: Evgeny
#> repository: https://CRAN.R-project.org/package=jsonvalidate
#> repository-code: https://github.com/ropensci/jsonvalidate
#> url: https://docs.ropensci.org/jsonvalidate/
#> date-released: '2025-02-07'
#> contact:
#> - family-names: FitzJohn
#>   given-names: Rich
#>   email: rich.fitzjohn@gmail.com
#> keywords:
#> - json
#> - json-validation
#> - jsonvalidate
#> - r
#> - r-package
#> - rstats
#> references:
#> - type: software
#>   title: R6
#>   abstract: 'R6: Encapsulated Classes with Reference Semantics'
#>   notes: Imports
#>   url: https://r6.r-lib.org
#>   repository: https://CRAN.R-project.org/package=R6
#>   authors:
#>   - family-names: Chang
#>     given-names: Winston
#>     email: winston@posit.co
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.R6
#> - type: software
#>   title: V8
#>   abstract: 'V8: Embedded JavaScript and WebAssembly Engine for R'
#>   notes: Imports
#>   url: https://jeroen.r-universe.dev/V8
#>   repository: https://CRAN.R-project.org/package=V8
#>   authors:
#>   - family-names: Ooms
#>     given-names: Jeroen
#>     email: jeroenooms@gmail.com
#>     orcid: https://orcid.org/0000-0002-4035-0289
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.V8
#> - type: software
#>   title: knitr
#>   abstract: 'knitr: A General-Purpose Package for Dynamic Report Generation in R'
#>   notes: Suggests
#>   url: https://yihui.org/knitr/
#>   repository: https://CRAN.R-project.org/package=knitr
#>   authors:
#>   - family-names: Xie
#>     given-names: Yihui
#>     email: xie@yihui.name
#>     orcid: https://orcid.org/0000-0003-0645-5666
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.knitr
#> - type: software
#>   title: jsonlite
#>   abstract: 'jsonlite: A Simple and Robust JSON Parser and Generator for R'
#>   notes: Suggests
#>   url: https://jeroen.r-universe.dev/jsonlite
#>   repository: https://CRAN.R-project.org/package=jsonlite
#>   authors:
#>   - family-names: Ooms
#>     given-names: Jeroen
#>     email: jeroenooms@gmail.com
#>     orcid: https://orcid.org/0000-0002-4035-0289
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.jsonlite
#> - type: software
#>   title: rmarkdown
#>   abstract: 'rmarkdown: Dynamic Documents for R'
#>   notes: Suggests
#>   url: https://pkgs.rstudio.com/rmarkdown/
#>   repository: https://CRAN.R-project.org/package=rmarkdown
#>   authors:
#>   - family-names: Allaire
#>     given-names: JJ
#>     email: jj@posit.co
#>   - family-names: Xie
#>     given-names: Yihui
#>     email: xie@yihui.name
#>     orcid: https://orcid.org/0000-0003-0645-5666
#>   - family-names: Dervieux
#>     given-names: Christophe
#>     email: cderv@posit.co
#>     orcid: https://orcid.org/0000-0003-4474-2498
#>   - family-names: McPherson
#>     given-names: Jonathan
#>     email: jonathan@posit.co
#>   - family-names: Luraschi
#>     given-names: Javier
#>   - family-names: Ushey
#>     given-names: Kevin
#>     email: kevin@posit.co
#>   - family-names: Atkins
#>     given-names: Aron
#>     email: aron@posit.co
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: hadley@posit.co
#>   - family-names: Cheng
#>     given-names: Joe
#>     email: joe@posit.co
#>   - family-names: Chang
#>     given-names: Winston
#>     email: winston@posit.co
#>   - family-names: Iannone
#>     given-names: Richard
#>     email: rich@posit.co
#>     orcid: https://orcid.org/0000-0003-3925-190X
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.rmarkdown
#> - type: software
#>   title: testthat
#>   abstract: 'testthat: Unit Testing for R'
#>   notes: Suggests
#>   url: https://testthat.r-lib.org
#>   repository: https://CRAN.R-project.org/package=testthat
#>   authors:
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: hadley@posit.co
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.testthat
#> - type: software
#>   title: withr
#>   abstract: 'withr: Run Code ''With'' Temporarily Modified Global State'
#>   notes: Suggests
#>   url: https://withr.r-lib.org
#>   repository: https://CRAN.R-project.org/package=withr
#>   authors:
#>   - family-names: Hester
#>     given-names: Jim
#>   - family-names: Henry
#>     given-names: Lionel
#>     email: lionel@posit.co
#>   - family-names: Müller
#>     given-names: Kirill
#>     email: krlmlr+r@mailbox.org
#>   - family-names: Ushey
#>     given-names: Kevin
#>     email: kevinushey@gmail.com
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: hadley@posit.co
#>   - family-names: Chang
#>     given-names: Winston
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.withr

# Check keywords.
jsonval$keywords
#> [1] "json"            "json-validation" "jsonvalidate"    "r"              
#> [5] "r-package"       "rstats"

# The repository.
jsonval$`repository-code`
#> [1] "https://github.com/ropensci/jsonvalidate"

Back to Table 1.

license

This key is extracted from the "License" field of the DESCRIPTION file.

Example 
cff_obj <- cff_create("yaml")

cat(cff_obj$license)
#> BSD-3-Clause

pkg <- desc::desc(file.path(find.package("yaml"), "DESCRIPTION"))

cat(pkg$get("License"))
#> BSD_3_clause + file LICENSE

Back to Table 1.

license-url

This key is not extracted from package metadata. See its description in the Guide to CFF schema v1.2.0.

Back to Table 1.

message

This key is generated from the package metadata with this template:

msg <- paste0(
  'To cite package "',
  "NAME_OF_THE_PACKAGE",
  '" in publications use:'
)
Example 
cat(cff_create("jsonlite")$message)
#> To cite package "jsonlite" in publications use:

Back to Table 1.

preferred-citation

This key is extracted from inst/CITATION. If multiple references are provided, it selects the first citation as the "preferred-citation" and the rest of them as references.

Example 
cffobj <- cff_create("rmarkdown")

cffobj$`preferred-citation`
#> type: manual
#> title: 'rmarkdown: Dynamic Documents for R'
#> authors:
#> - family-names: Allaire
#>   given-names: JJ
#>   email: jj@posit.co
#> - family-names: Xie
#>   given-names: Yihui
#>   email: xie@yihui.name
#>   orcid: https://orcid.org/0000-0003-0645-5666
#> - family-names: Dervieux
#>   given-names: Christophe
#>   email: cderv@posit.co
#>   orcid: https://orcid.org/0000-0003-4474-2498
#> - family-names: McPherson
#>   given-names: Jonathan
#>   email: jonathan@posit.co
#> - family-names: Luraschi
#>   given-names: Javier
#> - family-names: Ushey
#>   given-names: Kevin
#>   email: kevin@posit.co
#> - family-names: Atkins
#>   given-names: Aron
#>   email: aron@posit.co
#> - family-names: Wickham
#>   given-names: Hadley
#>   email: hadley@posit.co
#> - family-names: Cheng
#>   given-names: Joe
#>   email: joe@posit.co
#> - family-names: Chang
#>   given-names: Winston
#>   email: winston@posit.co
#> - family-names: Iannone
#>   given-names: Richard
#>   email: rich@posit.co
#>   orcid: https://orcid.org/0000-0003-3925-190X
#> year: '2026'
#> notes: R package version 2.31
#> url: https://github.com/rstudio/rmarkdown

citation("rmarkdown")[1]
#> Allaire J, Xie Y, Dervieux C, McPherson J, Luraschi J, Ushey K, Atkins
#> A, Wickham H, Cheng J, Chang W, Iannone R (2026). _rmarkdown: Dynamic
#> Documents for R_. R package version 2.31,
#> <https://github.com/rstudio/rmarkdown>.
#> 
#> A BibTeX entry for LaTeX users is
#> 
#>   @Manual{,
#>     title = {rmarkdown: Dynamic Documents for R},
#>     author = {JJ Allaire and Yihui Xie and Christophe Dervieux and Jonathan McPherson and Javier Luraschi and Kevin Ushey and Aron Atkins and Hadley Wickham and Joe Cheng and Winston Chang and Richard Iannone},
#>     year = {2026},
#>     note = {R package version 2.31},
#>     url = {https://github.com/rstudio/rmarkdown},
#>   }

Back to Table 1.

references

This key is extracted from inst/CITATION if multiple references are provided. The first citation is considered as the preferred-citation and the rest of them as "references". It also extracts package dependencies and adds them to this field using citation(auto = TRUE) on each dependency.

Example 
cffobj <- cff_create("rmarkdown")

cffobj$references
#> - type: book
#>   title: 'R Markdown: The Definitive Guide'
#>   authors:
#>   - family-names: Xie
#>     given-names: Yihui
#>   - family-names: Allaire
#>     given-names: J.J.
#>   - family-names: Grolemund
#>     given-names: Garrett
#>   publisher:
#>     name: Chapman and Hall/CRC
#>     address: Boca Raton, Florida
#>   year: '2018'
#>   isbn: '9781138359338'
#>   url: https://yihui.org/rmarkdown/
#> - type: book
#>   title: R Markdown Cookbook
#>   authors:
#>   - family-names: Xie
#>     given-names: Yihui
#>   - family-names: Dervieux
#>     given-names: Christophe
#>   - family-names: Riederer
#>     given-names: Emily
#>   publisher:
#>     name: Chapman and Hall/CRC
#>     address: Boca Raton, Florida
#>   year: '2020'
#>   isbn: '9780367563837'
#>   url: https://yihui.org/rmarkdown-cookbook
#> - type: software
#>   title: 'R: A Language and Environment for Statistical Computing'
#>   notes: Depends
#>   url: https://www.R-project.org/
#>   authors:
#>   - name: R Core Team
#>     website: https://ror.org/02zz1nj61
#>   institution:
#>     name: R Foundation for Statistical Computing
#>     website: https://ror.org/05qewa988
#>     address: Vienna, Austria
#>   year: '2026'
#>   doi: 10.32614/R.manuals
#>   version: '>= 3.0'
#> - type: software
#>   title: bslib
#>   abstract: 'bslib: Custom ''Bootstrap'' ''Sass'' Themes for ''shiny'' and ''rmarkdown'''
#>   notes: Imports
#>   url: https://rstudio.github.io/bslib/
#>   repository: https://CRAN.R-project.org/package=bslib
#>   authors:
#>   - family-names: Sievert
#>     given-names: Carson
#>     email: carson@posit.co
#>     orcid: https://orcid.org/0000-0002-4958-2844
#>   - family-names: Cheng
#>     given-names: Joe
#>     email: joe@posit.co
#>   - family-names: Aden-Buie
#>     given-names: Garrick
#>     email: garrick@posit.co
#>     orcid: https://orcid.org/0000-0002-7111-0077
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.bslib
#>   version: '>= 0.2.5.1'
#> - type: software
#>   title: evaluate
#>   abstract: 'evaluate: Parsing and Evaluation Tools that Provide More Details than
#>     the Default'
#>   notes: Imports
#>   url: https://evaluate.r-lib.org/
#>   repository: https://CRAN.R-project.org/package=evaluate
#>   authors:
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: hadley@posit.co
#>   - family-names: Xie
#>     given-names: Yihui
#>     orcid: https://orcid.org/0000-0003-0645-5666
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.evaluate
#>   version: '>= 0.13'
#> - type: software
#>   title: fontawesome
#>   abstract: 'fontawesome: Easily Work with ''Font Awesome'' Icons'
#>   notes: Imports
#>   url: https://rstudio.github.io/fontawesome/
#>   repository: https://CRAN.R-project.org/package=fontawesome
#>   authors:
#>   - family-names: Iannone
#>     given-names: Richard
#>     email: rich@posit.co
#>     orcid: https://orcid.org/0000-0003-3925-190X
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.fontawesome
#>   version: '>= 0.5.0'
#> - type: software
#>   title: htmltools
#>   abstract: 'htmltools: Tools for HTML'
#>   notes: Imports
#>   url: https://rstudio.github.io/htmltools/
#>   repository: https://CRAN.R-project.org/package=htmltools
#>   authors:
#>   - family-names: Cheng
#>     given-names: Joe
#>     email: joe@posit.co
#>   - family-names: Sievert
#>     given-names: Carson
#>     email: carson@posit.co
#>     orcid: https://orcid.org/0000-0002-4958-2844
#>   - family-names: Schloerke
#>     given-names: Barret
#>     email: barret@posit.co
#>     orcid: https://orcid.org/0000-0001-9986-114X
#>   - family-names: Chang
#>     given-names: Winston
#>     email: winston@posit.co
#>     orcid: https://orcid.org/0000-0002-1576-2126
#>   - family-names: Xie
#>     given-names: Yihui
#>     email: yihui@posit.co
#>   - family-names: Allen
#>     given-names: Jeff
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.htmltools
#>   version: '>= 0.5.1'
#> - type: software
#>   title: jquerylib
#>   abstract: 'jquerylib: Obtain ''jQuery'' as an HTML Dependency Object'
#>   notes: Imports
#>   repository: https://CRAN.R-project.org/package=jquerylib
#>   authors:
#>   - family-names: Sievert
#>     given-names: Carson
#>     email: carson@rstudio.com
#>     orcid: https://orcid.org/0000-0002-4958-2844
#>   - family-names: Cheng
#>     given-names: Joe
#>     email: joe@rstudio.com
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.jquerylib
#> - type: software
#>   title: jsonlite
#>   abstract: 'jsonlite: A Simple and Robust JSON Parser and Generator for R'
#>   notes: Imports
#>   url: https://jeroen.r-universe.dev/jsonlite
#>   repository: https://CRAN.R-project.org/package=jsonlite
#>   authors:
#>   - family-names: Ooms
#>     given-names: Jeroen
#>     email: jeroenooms@gmail.com
#>     orcid: https://orcid.org/0000-0002-4035-0289
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.jsonlite
#> - type: software
#>   title: knitr
#>   abstract: 'knitr: A General-Purpose Package for Dynamic Report Generation in R'
#>   notes: Imports
#>   url: https://yihui.org/knitr/
#>   repository: https://CRAN.R-project.org/package=knitr
#>   authors:
#>   - family-names: Xie
#>     given-names: Yihui
#>     email: xie@yihui.name
#>     orcid: https://orcid.org/0000-0003-0645-5666
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.knitr
#>   version: '>= 1.43'
#> - type: software
#>   title: methods
#>   abstract: 'R: A Language and Environment for Statistical Computing'
#>   notes: Imports
#>   authors:
#>   - name: R Core Team
#>     website: https://ror.org/02zz1nj61
#>   institution:
#>     name: R Foundation for Statistical Computing
#>     website: https://ror.org/05qewa988
#>     address: Vienna, Austria
#>   year: '2026'
#>   doi: 10.32614/R.manuals
#> - type: software
#>   title: tinytex
#>   abstract: 'tinytex: Helper Functions to Install and Maintain TeX Live, and Compile
#>     LaTeX Documents'
#>   notes: Imports
#>   url: https://github.com/rstudio/tinytex
#>   repository: https://CRAN.R-project.org/package=tinytex
#>   authors:
#>   - family-names: Xie
#>     given-names: Yihui
#>     email: xie@yihui.name
#>     orcid: https://orcid.org/0000-0003-0645-5666
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.tinytex
#>   version: '>= 0.31'
#> - type: software
#>   title: tools
#>   abstract: 'R: A Language and Environment for Statistical Computing'
#>   notes: Imports
#>   authors:
#>   - name: R Core Team
#>     website: https://ror.org/02zz1nj61
#>   institution:
#>     name: R Foundation for Statistical Computing
#>     website: https://ror.org/05qewa988
#>     address: Vienna, Austria
#>   year: '2026'
#>   doi: 10.32614/R.manuals
#> - type: software
#>   title: utils
#>   abstract: 'R: A Language and Environment for Statistical Computing'
#>   notes: Imports
#>   authors:
#>   - name: R Core Team
#>     website: https://ror.org/02zz1nj61
#>   institution:
#>     name: R Foundation for Statistical Computing
#>     website: https://ror.org/05qewa988
#>     address: Vienna, Austria
#>   year: '2026'
#>   doi: 10.32614/R.manuals
#> - type: software
#>   title: xfun
#>   abstract: 'xfun: Supporting Functions for Packages Maintained by ''Yihui Xie'''
#>   notes: Imports
#>   url: https://github.com/yihui/xfun
#>   repository: https://CRAN.R-project.org/package=xfun
#>   authors:
#>   - family-names: Xie
#>     given-names: Yihui
#>     email: xie@yihui.name
#>     orcid: https://orcid.org/0000-0003-0645-5666
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.xfun
#>   version: '>= 0.36'
#> - type: software
#>   title: yaml
#>   abstract: 'yaml: Methods to Convert R Data to YAML and Back'
#>   notes: Imports
#>   url: https://yaml.r-lib.org
#>   repository: https://CRAN.R-project.org/package=yaml
#>   authors:
#>   - family-names: Stephens
#>     given-names: Jeremy
#>   - family-names: Simonov
#>     given-names: Kirill
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.yaml
#>   version: '>= 2.1.19'
#> - type: software
#>   title: digest
#>   abstract: 'digest: Create Compact Hash Digests of R Objects'
#>   notes: Suggests
#>   url: https://eddelbuettel.github.io/digest/
#>   repository: https://CRAN.R-project.org/package=digest
#>   authors:
#>   - family-names: Eddelbuettel
#>     given-names: Dirk
#>     email: edd@debian.org
#>     orcid: https://orcid.org/0000-0001-6419-907X
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.digest
#> - type: software
#>   title: fs
#>   abstract: 'fs: Cross-Platform File System Operations Based on ''libuv'''
#>   notes: Suggests
#>   url: https://fs.r-lib.org
#>   repository: https://CRAN.R-project.org/package=fs
#>   authors:
#>   - family-names: Hester
#>     given-names: Jim
#>   - family-names: Wickham
#>     given-names: Hadley
#>   - family-names: Csárdi
#>     given-names: Gábor
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.fs
#> - type: software
#>   title: downlit
#>   abstract: 'downlit: Syntax Highlighting and Automatic Linking'
#>   notes: Suggests
#>   url: https://downlit.r-lib.org/
#>   repository: https://CRAN.R-project.org/package=downlit
#>   authors:
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: hadley@posit.co
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.downlit
#>   version: '>= 0.4.0'
#> - type: software
#>   title: sass
#>   abstract: 'sass: Syntactically Awesome Style Sheets (''Sass'')'
#>   notes: Suggests
#>   url: https://rstudio.github.io/sass/
#>   repository: https://CRAN.R-project.org/package=sass
#>   authors:
#>   - family-names: Cheng
#>     given-names: Joe
#>     email: joe@rstudio.com
#>   - family-names: Mastny
#>     given-names: Timothy
#>     email: tim.mastny@gmail.com
#>   - family-names: Iannone
#>     given-names: Richard
#>     email: rich@rstudio.com
#>     orcid: https://orcid.org/0000-0003-3925-190X
#>   - family-names: Schloerke
#>     given-names: Barret
#>     email: barret@rstudio.com
#>     orcid: https://orcid.org/0000-0001-9986-114X
#>   - family-names: Sievert
#>     given-names: Carson
#>     email: carson@rstudio.com
#>     orcid: https://orcid.org/0000-0002-4958-2844
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.sass
#>   version: '>= 0.4.0'
#> - type: software
#>   title: shiny
#>   abstract: 'shiny: Web Application Framework for R'
#>   notes: Suggests
#>   url: https://shiny.posit.co/
#>   repository: https://CRAN.R-project.org/package=shiny
#>   authors:
#>   - family-names: Chang
#>     given-names: Winston
#>     email: winston@posit.co
#>     orcid: https://orcid.org/0000-0002-1576-2126
#>   - family-names: Cheng
#>     given-names: Joe
#>     email: joe@posit.co
#>   - family-names: Allaire
#>     given-names: JJ
#>     email: jj@posit.co
#>   - family-names: Sievert
#>     given-names: Carson
#>     email: carson@posit.co
#>     orcid: https://orcid.org/0000-0002-4958-2844
#>   - family-names: Schloerke
#>     given-names: Barret
#>     email: barret@posit.co
#>     orcid: https://orcid.org/0000-0001-9986-114X
#>   - family-names: Aden-Buie
#>     given-names: Garrick
#>     email: garrick@adenbuie.com
#>     orcid: https://orcid.org/0000-0002-7111-0077
#>   - family-names: Xie
#>     given-names: Yihui
#>     email: yihui@posit.co
#>   - family-names: Allen
#>     given-names: Jeff
#>   - family-names: McPherson
#>     given-names: Jonathan
#>     email: jonathan@posit.co
#>   - family-names: Dipert
#>     given-names: Alan
#>   - family-names: Borges
#>     given-names: Barbara
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.shiny
#>   version: '>= 1.6.0'
#> - type: software
#>   title: testthat
#>   abstract: 'testthat: Unit Testing for R'
#>   notes: Suggests
#>   url: https://testthat.r-lib.org
#>   repository: https://CRAN.R-project.org/package=testthat
#>   authors:
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: hadley@posit.co
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.testthat
#>   version: '>= 3.0.3'
#> - type: software
#>   title: tibble
#>   abstract: 'tibble: Simple Data Frames'
#>   notes: Suggests
#>   url: https://tibble.tidyverse.org/
#>   repository: https://CRAN.R-project.org/package=tibble
#>   authors:
#>   - family-names: Müller
#>     given-names: Kirill
#>     email: kirill@cynkra.com
#>     orcid: https://orcid.org/0000-0002-1416-3412
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: hadley@rstudio.com
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.tibble
#> - type: software
#>   title: vctrs
#>   abstract: 'vctrs: Vector Helpers'
#>   notes: Suggests
#>   url: https://vctrs.r-lib.org/
#>   repository: https://CRAN.R-project.org/package=vctrs
#>   authors:
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: hadley@posit.co
#>   - family-names: Henry
#>     given-names: Lionel
#>     email: lionel@posit.co
#>   - family-names: Vaughan
#>     given-names: Davis
#>     email: davis@posit.co
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.vctrs
#> - type: software
#>   title: withr
#>   abstract: 'withr: Run Code ''With'' Temporarily Modified Global State'
#>   notes: Suggests
#>   url: https://withr.r-lib.org
#>   repository: https://CRAN.R-project.org/package=withr
#>   authors:
#>   - family-names: Hester
#>     given-names: Jim
#>   - family-names: Henry
#>     given-names: Lionel
#>     email: lionel@posit.co
#>   - family-names: Müller
#>     given-names: Kirill
#>     email: krlmlr+r@mailbox.org
#>   - family-names: Ushey
#>     given-names: Kevin
#>     email: kevinushey@gmail.com
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: hadley@posit.co
#>   - family-names: Chang
#>     given-names: Winston
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.withr
#>   version: '>= 2.4.2'
#> - type: software
#>   title: xml2
#>   abstract: 'xml2: Parse XML'
#>   notes: Suggests
#>   url: https://xml2.r-lib.org
#>   repository: https://CRAN.R-project.org/package=xml2
#>   authors:
#>   - family-names: Wickham
#>     given-names: Hadley
#>   - family-names: Hester
#>     given-names: Jim
#>   - family-names: Ooms
#>     given-names: Jeroen
#>     email: jeroenooms@gmail.com
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.xml2

citation("rmarkdown")[-1]
#> Xie Y, Allaire J, Grolemund G (2018). _R Markdown: The Definitive
#> Guide_. Chapman and Hall/CRC, Boca Raton, Florida. ISBN 9781138359338.
#> <https://yihui.org/rmarkdown/>.
#> 
#> Xie Y, Dervieux C, Riederer E (2020). _R Markdown Cookbook_. Chapman
#> and Hall/CRC, Boca Raton, Florida. ISBN 9780367563837.
#> <https://yihui.org/rmarkdown-cookbook>.
#> 
#> To see these entries in BibTeX format, use 'print(<citation>,
#> bibtex=TRUE)', 'toBibtex(.)', or set
#> 'options(citation.bibtex.max=999)'.

Back to Table 1.

repository

This key is extracted from the "Repository" field of the DESCRIPTION file. Usually, this field is automatically populated when a package is hosted on a repository (like CRAN or the r-universe). For packages without this field in the DESCRIPTION (which is the typical case for an in-development package), cffr tries to find the package in any of the default repositories specified in options("repos").

In the case of Bioconductor packages, those are identified if a “biocViews” is present in the DESCRIPTION file.

If cffr detects that the package is available on CRAN, it returns the canonical URL form of the package (that is, https://CRAN.R-project.org/package=jsonlite).

Example 
# Use an installed package.

inst <- cff_create("jsonlite")

cat(inst$repository)
#> https://CRAN.R-project.org/package=jsonlite

# Demo file downloaded from the r-universe.

runiv <- system.file("examples/DESCRIPTION_r_universe", package = "cffr")
runiv_cff <- cff_create(runiv)

cat(runiv_cff$repository)
#> https://ropensci.r-universe.dev

desc::desc(runiv)$get("Repository")
#>                        Repository 
#> "https://ropensci.r-universe.dev"

# For an in-development package.

norepo <- system.file("examples/DESCRIPTION_basic", package = "cffr")

# No repository is available.
norepo_cff <- cff_create(norepo)

cat(norepo_cff[["repository"]])

# Change the name to a known package on CRAN: ggplot2.

tmp <- tempfile("DESCRIPTION")
file.copy(norepo, tmp)
#> [1] TRUE

# Change the package name.
desc::desc_set("Package", "ggplot2", file = tmp)
#> Type: Package
#> Package: ggplot2
#> Title: A Basic Description
#> Version: 0.1.6
#> Authors@R (parsed):
#>     * Marc Basic <marcbasic@gmail.com> [aut, cre, cph]
#> Description: A very basic description. Should parse without problems.
#> License: GPL-3
#> URL: https://github.com/basic/package, https://basic.github.io/package
#> BugReports: https://github.com/basic/package/issues
#> Encoding: UTF-8
#> LazyData: true
#> RoxygenNote: 6.0.1.9000

cat(cff_create(tmp)[["repository"]])
#> https://CRAN.R-project.org/package=ggplot2

Back to Table 1.

repository-artifact

This key is not extracted from package metadata. See its description in the Guide to CFF schema v1.2.0.

Back to Table 1.

repository-code

This key is extracted from the "BugReports" or "URL" fields in the DESCRIPTION file. cffr tries to identify the URL of the source on the following repositories:

Example 
# Installed package on GitHub.

cat(cff_create("jsonlite")$`repository-code`)
#> https://github.com/jeroen/jsonlite

# GitLab

gitlab <- system.file("examples/DESCRIPTION_gitlab", package = "cffr")

cat(cff_create(gitlab)$`repository-code`)
#> https://gitlab.com/ninijay/methoden

# Codeberg
codeberg <- system.file("examples/DESCRIPTION_codeberg", package = "cffr")

cat(cff_create(codeberg)$`repository-code`)
#> https://codeberg.org/dgkf/options

Back to Table 1.

title

This key is extracted from the "Description" field of the DESCRIPTION file.

title <- paste0("NAME_OF_THE_PACKAGE", ": ", "TITLE_OF_THE_PACKAGE")
Example 
# Use an installed package.

cat(cff_create("testthat")$title)
#> testthat: Unit Testing for R

Back to Table 1.

type

Fixed value equal to "software". The other possible value is "dataset". See the description on the Guide to CFF schema v1.2.0.

Back to Table 1.

url

This key is extracted from the "BugReports" or "URL" fields in the DESCRIPTION file. It corresponds to the first URL that is different from repository-code.

Example 
# Many URLs.
manyurls <- system.file("examples/DESCRIPTION_many_urls", package = "cffr")

cat(cff_create(manyurls)$url)
#> https://test.github.io/package/

# Check the source metadata.

desc::desc(manyurls)
#> Type: Package
#> Package: manyurls
#> Title: A lot of urls
#> Version: 0.1.6
#> Authors@R (parsed):
#>     * Marc Basic <marcbasic@gmail.com> [aut, cre, cph]
#> Description: This package has many urls. Specifically, 1 Bug Reports and 6
#>     URLs. Expected is to have 1 repository-code, 1 url and 3 URLs, since
#>     there is 1 duplicate and 1 invalid url.
#> License: GPL-3
#> URL: https://github.com/test/package, https://test.github.io/package/,
#>     https://r-forge.r-project.org/projects/test/, http://google.ru,
#>     https://gitlab.com/r-packages/behaviorchange, this.is.not.an.url
#> BugReports: https://github.com/test/package/issues
#> Encoding: UTF-8

Back to Table 1.

version

This key is extracted from the "Version" field in the DESCRIPTION file.

# Should be (>= 3.0.0).
cat(cff_create("testthat")$version)
#> 3.3.2

Back to Table 1.

References

Druskat, Stephan, Jurriaan H. Spaaks, Neil Chue Hong, et al. 2021. Citation File Format. https://doi.org/10.5281/zenodo.5171937.