Tag 16 = 0?

Imported from previous forum

[ original email was from Robert McWhirter - robert.mcwhirter@swx.ch ]
The spec says that for tag 16, EndSeqNo, iy is of type SeqNo, which Vol. 1 still defines as positive Integer. The contents can be zero, however:

“Message sequence number of last message in range to be resent. If request is for a single message BeginSeqNo (7) = EndSeqNo. If request is for all messages subsequent to a particular message, EndSeqNo = “0” (representing infinity).”

Should the datatype for this tag be changed? At least one FIX s/w vendor I know has updated his definition of SeqNum type, to allow 0, which I think is wrong…