Testcase for non numeric FIXTag

Imported from previous forum

My test broker sent a FIX message where one of the field was intenionally specified as

^X=123^

and the counterparty’s FIX.4.2 engine crashed

Where can I find a documented testcase which states that the counterparty should reject the message which has non numeric FIX Tag?

Is 14.f. “Receive message with a value in an incorrect data format (syntax) for a particular field identifier (tag number).” on page 53 / 63 of FIX 4.3 with Errata 20020920 - Volume 2 dated September 20, 2002 the nearest match to the testcase I am looking for? or is the 14.f test case more specific to reject for example ^44=ABCD^?