here is the actual recommendation:
Should be set to “ordering disabled”, when the MFS interfaces with :
– an Ericsson SGSN
– or any SGSN modifying the PDU Lifetime value (during data flows addressed to the same MS on the same LLC SAPI) in a non-acceptable manner
–> otherwise should be set to “ordering enabled”.
By default, it is ENABLED.
It is not changeable, except internally, by ALU teams.
Basically, there is no reason for not wanting to re-order the PDUs before sending them to the MS, except when interfacing with specific SGSN. This parameter was probably used to improve compatibility with *old* SGSN, in the past.