GL references are used to group related transactions together within a journal.
When making entries into GL Journal Entry, you may assign a Reference number to a group of transactions that net to zero. For instance, when making a monthly entry to record over/under billings, you could give the same reference number to all debits and credits related to this entry. If using standard monthly journal entries, you may reuse this number each month. Although it is not necessary, you may then enter descriptions and notes regarding these entries in GL Journal References.
You can use the same reference number for all transactions entered in GL for a month. If you use the same reference number for related transactions, and then go back later and add more related entries, the use of the same unique reference number will allow you to group these together on journal reports even though their transaction numbers are out of sequence.
Most entries in GL come from interfaces from other modules. The GL Reference for all interfaced transactions will be the batch id number. Therefore, these numbers will also associate one reference number with a group of related transactions that net to zero.