Is there any rule in SCORM 1.2 regarding the use of extended ASCII characters in data sent to the lms?
No rule, per se. The specification indicates that you should support "a set of ASCII characters", nothing more, well, specific. This is one of the places where we focus on interoperability over the letter of the standard (as discussed in this post). Put simply, we would recommend that you are conservative in what you send and liberal in what you accept.
- Content should be conservative. Unless there's a compelling reason to use an extended set of characters, don't. It will create headaches.
- LMSs should be flexible. To whatever degree possible, accept the largest set of characters possible. Stretch. It will reduce headaches long term.