Ah thanks. I thought I used case sensitive replace-regexp before, but probably I am mistaking then. Section "34.3 Regular Expressions" of the Emacs manual states that "[a-z]" or "[:lower:]" should match only lower case, while it is not mentioned at all that it will not work by default (case-fold-search as well as reb-toggle-case and reb-change-syntax are not mentioned at all in that section as far as I can find). Indeed I was referring to the docstring of re-builder. Anyway, I am happy to provide a patch. On Thu, 1 Apr 2021 at 00:25, Basil L. Contovounesios wrote: > dalanicolai writes: > > > When using the regexp builder and trying to match only lower case > > letters (and spaces), Emacs also includes upper case matches. > > I think this is the effect of the user option case-fold-search, which > defaults to non-nil (this is the case across most search-related parts > of Emacs, including Isearch). You can toggle it in re-builder > specifically with C-c C-c (reb-toggle-case), or across all buffers by > customising case-fold-search to be nil. > > > Also, I am unable to find in the manual any information about the > > option of setting different syntaxes in the regexp builder > > I think most of the documentation for re-builder.el is in its commentary > at the start of the file; see M-x find-library RET re-builder RET. > > I haven't used re-builder much, but from M-x customize-group RET > re-builder RET I see there is a user option reb-re-syntax for > controlling the default syntax. C-h m in the re-builder buffer further > reveals that the command C-c C-i (reb-change-syntax) can modify > reb-re-syntax on the fly. > > > (also the option is not mentioned in the regexp-builder docstring). So > > I would additionally like to report this as a documentation bug. > > Are you referring to the docstring of the re-builder command, or > something else? And is it a listing of key bindings you would like to > see, or something else? Would you like to provide a patch with > suggestions for improvements? > > Thanks, > > -- > Basil >