Identifier for Trading Session
Can be used to represent a specific market trading session (e.g. "PRE-OPEN", "CROSS_2", "AFTER-HOURS", "TOSTNET", "TOSTNET2", etc).
Values should be bi-laterally agreed to between counterparties.
Firms may register Trading Session values on the FIX website (presently a document maintained within "ECN and Exchanges" working group section).