Security: F_data_not is not being handled leading to invalid read or write.

Security: F_data_not is not being handled leading to invalid read or write.

At some point I changed the behavior to return F_data_not when the main string (usually buffer) has used set to 0.
I failed to update the FSS processing functions to handle this.

The documentation comments are also not up to date in this regard and is now updated.