A variable length information element which has a code value lower than the code value of the variable length information element preceding it shall be considered as an out of sequence information element
If the network or user receives a message containing an out of sequence information element, it may ignore this information element and continue to process the message. If this information is mandatory, and the network or user chooses to ignore this out of sequence information element, then the error handling procedure for missing mandatory information elements as described in 5.8.6.1 shall be followed. If the ignored information element is non-mandatory, the receiver continues to process the message.
Note - Some implementations may choose to process all the information elements received in a message regardless of the order in which they are placed.