How to determine the version of Mail.dat files that MailStream Plus produced

MailStream Plus, all versions, all platforms
Often Mail.dat files are referred to by just 2 numbers, such as 17.1 or 17-1. 
But there actually are 4 numbers in the full version number, such as

There are two ways to determine the version. 

The first two numbers are in the Mail.dat HDR file in Field Code HDR-1101 "Idealliance Version".  In the 17-1 and 15-1 version files that field is in position 9-12.
In 17-1 and later versions, you can also see the last two numbers, in Field Code HDR-1192 "Mail.dat Revision", which is position 228-232 in 17-1 version files. 
Prior to Mail.dat version 17-1, the last two numbers were not available in the Mail.dat files. 

MailStream Plus produces a report that gives the full version number, record counts for each of the Mail.dat files, and other information.  By default it goes into the RPT output file (PRNTRPT on IBMi, DD MSRPRPT on z/OS, DD_MSRPRPT on Windows and UNIX/Linux.)  
But the MAILDAT report may go to another location depending on what is in position 60-67 on the REPORT MAILDAT parameter in the job.
The first few lines of the report are like this, and the full version number is given on the "IDEAlliance Version" line.

MSRP00 -- MailStream Plus Reporting, R08.3M03,                                  MSRPMD00 -- Mail.dat                          1

                                  Job ID: IVP
                     IDEAlliance Version: 
UPDATED:  August 9, 2017