Field ClOrdID (11) - FIX Protocol FIX.4.2
Unique identifier for Order as assigned by institution (identified by SenderCompID or OnBehalfOfCompID as appropriate). Uniqueness must be guaranteed within a single trading day. Firms, particularly those which electronically submit multi-day orders, trade globally or throughout market close periods,should ensure uniqueness across days, for example by embedding a date within the ClOrdID (11) field.
Added in protocol FIX.2.7