In all versions of Regina (up to and including 3.7),
using the following statement(s) fails:
/\*\*/ signal on novalue; options potatoes
Enclosing "potatoes" in quotes bypasses the error, or
removing the SIGNAL instruction.
The Regina PDF doesn't show that the options for the
OPTIONS are needed to be enclosed in (any kind of)
quotes, indeed, various examples don't use quotes.
Also, the PDF documentation doesn't show that the
options for the OPTIONS statement are (is) optional.
_________________________ Gerard Schildberger