ExpireTime

FIX Field 126

Tag	Name	Type	Enumerated	First introduced
126	ExpireTime	UTCTimestamp		FIX.4.0

Time/Date of order expiration (always expressed in UTC (Universal Time Coordinated, also known as "GMT")

The meaning of expiration is specific to the context where the field is used.

For orders, this is the expiration time of a Good Til Date TimeInForce.

For Quotes - this is the expiration of the quote.

Expiration time is provided across the quote message dialog to control the length of time of the overall quoting process.

For collateral requests, this is the time by which collateral must be assigned.

For collateral assignments, this is the time by which a response to the assignment is expected.

Notes

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Don't forget to refer to the FPL Discussion Groups to back up anything you write.
You will often find the authoritative statements on matters of FIX specification interpretation there.
Links from FIXwiki pages to relevant discussions on the FPL site are very valuable.

For example if you were writing a clarification on how to specify the "quantity" of an order in FIX, you might add the
following relevant link, http://www.fixprotocol.org/discuss/read/f5014573, to back up your points.