RE: [External] : Re: Is there a way of setting a variable only when it exists?

[Drew Adams]

> - what is user option?

C-h r
g Glossary
C-s User Option

  User Option
     A user option is a face (q.v.) or a variable (q.v.) that exists so
     that you can customize Emacs by setting it to a new value.  *Note
     Easy Customization::.

Personally, I think that definition isn't up-to-date.

Most places in Emacs, "option", aka "user option", aka
"user variable", aka "custom variable" means what you
can customize using `M-x customize-option'.  That is,
faces are not normally considered options.