API Suspend Data Limit

Just to expand a bit on Vincent's answer... The specification for Tin Can specifically allows any limit - it leaves it up to the LRS to decide (with the restriction that the limit can at least be configured to be high enough to allow the sizes the LRS conformance tests need):

"The LRS MAY choose any Attachment, Statement and document size limits and MAY vary this limit on any basis, e.g., per authority." (my emphasis)

The way Storyline saves suspend-data to TinCan is in a "document".

That said, it's highly unlikely that an LRS will enforce limits on documents as low as SCORM 1.2's limit on suspend-data (4096 characters) - or even SCORM 2004's (64000 characters).

But it's still worth being aware that it may, and that it's allowed to even vary that limit based on anything it likes. I.e. different courses may get different limits,different learners may get different limits - it might even base the limit on time of day ;-) It's all up to the individual LRS.