In the FIX protocol the ClOrdID field is the user supplied identifier for an inbound Order that the user will provide to identify the Order when acting on the Order. When referring to an exising Order the user will use the OrigClOrdID field to identify the ClOrdID of the Order in question.
Reference
String
20
The published identifier for this Reply_change. It is a string of characters that uniquely identifies every Reply_change in the system.
UpdateNumber
Integer (unsigned)
8
A number that records every change that happens to a record. It is primarily used to avoid write after read problems when an intermediate write has changed the originally read record.
BCSequence
Integer (unsigned)
8
The sequence number of this Reply_change message in the overall broadcast sequence.
Reloaded
Integer (unsigned)
1
Set to true for change records that are generated during a normal startup from engine cache files.