Library /sys$common/syshlp/pca$help.hlb SET, LANGUAGE, Description  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    The language setting determines how PCA parses symbol names in
    command input. If the language is set to C/C++, PCA treats symbol
    names as case-sensitive. Upper-case and lower-case letters are
    then treated as different characters. If the language is set to
    anything other than C/C++, symbol names are assumed to be case
    insensitive, and lowercase letters are treated as if they were
    uppercase letters.

    When you use the SET DATAFILE command, the language setting is
    determined by the language of the main routine in the program.
    Normally, you need not change this setting. However, if you have
    a mixed-language program which includes C/C++ modules, you may
    have to change the language setting before you can reference
    symbols that include lowercase letters.