In the URL removing the first character in a combination of strings and commands/tokens using \gobblechar of stringstrings, @JosephWright has suggested the command \ExplTitlecase (expl3) to capitalize the first word of a set of words set in lowercase.
In the following MWE, I have used Joseph Wright's \ExplTitlecase. I have shown Examples 1 to 4.
%MWE\documentclass{article}\newcommand*{\myMixedCaseCommand}[1]{#1}\ExplSyntaxOn\NewExpandableDocumentCommand{\ExplTitlecase}{m}{\text_titlecase:n { #1 }}\ExplSyntaxOff\begin{document}%Example 1\ExplTitlecase{first word will be capitalized}%Example 2\ExplTitlecase{a certain \uppercase{UPPERCASE} acronym within a set of words set in lowercase}%Example 3\ExplTitlecase{a certain \lowercase{lowercase} acronym within a set of words set in lowercase}%Example 4\ExplTitlecase{a certain \myMixedCaseCommand{MiXeDCaSe} acronym within a set of words set in lowercase}\end{document}The MWE compiles fine, and the output in Examples 1 to 3 are expected. However, what I would want for Example 4 is to find some kind of command, which I temporarily call \myMixedCaseCommand, such that this command preserves the mixed-case nature of the acronym MiXeDCaSe. In the output, MiXeDCaSe was lowercased and became mixedcase. I would want the output to be exactly MiXeDCaSe.
Kindly seeking any help.