A \gls*{short} is a \gls{command} whose \gls{argument} may not contain a paragraph break (either as a blank line or using \glsi{par}.) Conversely, a \keywordfmt{long command} is a command whose \gls{argument} may contain a paragraph break. Using short commands helps to test for forgotten braces, so it is recommended that when you \htmlref{define a new command}{ch:newcom}\latex{ (see \chapterref{ch:newcom})} you should always make the command a short command, unless there is a chance that the argument may need to contain a paragraph break.