A maximum of 99 lines of distribution can be imported at one time on one invoice record.  This 99 limit also applies to the number of distributions that one line of an invoice can have as well when importing.  For example, one invoice could have 99 lines of distribution, and each of those lines could be distributed to 99 projects, maximum.

This limit is determined by the number of extensions possible on the Fields tab of an import parameter.

When trying to import more than 99 lines of distribution you may receive Error: Extension cannot exceed 2 characters on the Fields tab of the import parameter.