it seems that in the case that more than two or more
commas are following each other without an intervening
blank (e.g. in an invocation where arguments are left
out), then the PDF rendering seems to err (a full
square is shown, indicating a missing glyph).
[That bug is shown in earlier versions of the PDF
renderings (e.g. for ooRexx 3.1) as well.]
p. 278 (p. 256), sample at the end of the page at the
end of the argument list in the NEW-message.
p. 294 (p. 271), sample at the end of the page,
argument list of the CreateMessage message
p. 295 (p. 272), sample at the top, argument list of