completion-styles-alist

completion-styles-alist is a variable defined in `minibuffer.el'.
Its value is

((emacs21 completion-emacs21-try-completion completion-emacs21-all-completions "Simple prefix-based completion.\nI.e. when completing \"foo_bar\" (where _ is the position of point),\nit will consider all completions candidates matching the glob\npattern \"foobar*\".")
 (emacs22 completion-emacs22-try-completion completion-emacs22-all-completions "Prefix completion that only operates on the text before point.\nI.e. when completing \"foo_bar\" (where _ is the position of point),\nit will consider all completions candidates matching the glob\npattern \"foo*\" and will add back \"bar\" to the end of it.")
 (basic completion-basic-try-completion completion-basic-all-completions "Completion of the prefix before point and the suffix after point.\nI.e. when completing \"foo_bar\" (where _ is the position of point),\nit will consider all completions candidates matching the glob\npattern \"foo*bar*\".")
 (partial-completion completion-pcm-try-completion completion-pcm-all-completions "Completion of multiple words, each one taken as a prefix.\nI.e. when completing \"l-co_h\" (where _ is the position of point),\nit will consider all completions candidates matching the glob\npattern \"l*-co*h*\".\nFurthermore, for completions that are done step by step in subfields,\nthe method is applied to all the preceding fields that do not yet match.\nE.g. C-x C-f /u/mo/s TAB could complete to /usr/monnier/src.\nAdditionally the user can use the char \"*\" as a glob pattern.")
 (substring completion-substring-try-completion completion-substring-all-completions "Completion of the string taken as a substring.\nI.e. when completing \"foo_bar\" (where _ is the position of point),\nit will consider all completions candidates matching the glob\npattern \"*foo*bar*\".")
 (initials completion-initials-try-completion completion-initials-all-completions "Completion of acronyms and initialisms.\nE.g. can complete M-x lch to list-command-history\nand C-x C-f ~/sew to ~/src/emacs/work."))

• This variable may be risky if used as a file-local variable.

Documentation:
List of available completion styles.
Each element has the form (NAME TRY-COMPLETION ALL-COMPLETIONS DOC):
where NAME is the name that should be used in `completion-styles',
TRY-COMPLETION is the function that does the completion (it should
follow the same calling convention as `completion-try-completion'),
ALL-COMPLETIONS is the function that lists the completions (it should
follow the calling convention of `completion-all-completions'),
and DOC describes the way this style of completion works.