MailStream Plus- IMb's rejected by USPS. Invalid IMb Service Type ID (with ALG PP pos 10=X)


The IMB is rejected by USPS. The MailStream Plus presort is set up as Full Service, with an incorrect Full Service STID (Service Type IDentifier) for a First-Class Letter mailing.    
IMBOUT 320 I                 C 300 300     A                        352




The ALG PP parameter position 10 has an 'X' for 'Do not verify STIDs. Use the assigned STIDs without changing them.'
This causes MailStream Plus
™ (MSP) to accept an incorrect STID value for Full Service 
The IMBOUT parameter has 300 in both positions 32-34 (non-auto) and in 36-38 (Basic/Full Service)

Another thing that ALG PP position 10=X can cause pre-assigned IMb's (i.e. IMbs passed through MSP in the input records), the X will cause MSP to not validate the IMb's at all.  Even records that do not have IMbs will be indicated as having valid IMb's in the Mail.dat files. Likewise, IMb's with incorrect length or have invalid characters, will be indicated as valid in the Mail.dat files. 
Although incorrect length or invalid characters in preassigned IMb's *will* cause the TADF generating program to abend, if it is activated via a value in positions 69-71 of the IMBINB or IMBOUT parameters. 


UPDATED: March 14, 2019
The USPS STID chart shows 260 is the correct value for Full Service First-Class..The RP INF parameter for MDMFSP should have an F or Y in position 35 for Full Service, which indicates that parameter IMBOUT position 36-38 needs to change to STID 260 for Full Service First-Class mail pieces. The STID 300 in 32-34 is correct for any NonAutomation pieces.

FYI- MSP will check the IMBOUT values and correct them or abend, based on the ALG PP parameter position 10 containing either (Y or F) or (N or B).
An X in position 10 of the ALG PP indicates to not verify the STID values, just use them as is.