Don't they contain `.' in their variable_name part (the part between
"static char *" and "[]" in the second line)?
The file "s1.dis.xpm" contains the following line:
static char *saveas.dis[] = {
The specification of XPM (http://koala.ilog.fr/lehors/doc/xpm.PS) does
not explicitly state the syntax of the variable_name. But I think it
is reasonable to assume that it coincides with that of identifiers in
C or C++, because XPM is designed so as to be included in these
languages. (Chapter 2 starts with "The XPM format presents a C
syntax".)
I could display s1.dis.xpm if the variable_name part is replaced with
`saveas_dis'.