Variable: bibtex-autokey-name-case-convert
bibtex-autokey-name-case-convert is an alias and customizable for
bibtex-autokey-name-case-convert-function, defined in bibtex.el.gz.
Value
downcase
Documentation
Function called for each name to perform case conversion.
See bibtex-generate-autokey for details.
Probably introduced at or before Emacs version 20.3.