Arbortext Editor 5,3m040 running on 64-bit Windows 7 SP1 with 4 Gig of RAM (8 Gig on some PCs).
Someone (the evidence points to me) set a preference or did something else that causes an SGML document to be saved without the doctype header.
The following came up on a help search, but I need to know which preference causes it to not be saved when exiting Arbortext Editor. Ensuring valid headers Make sure the instance file has a valid SGML header structure. Three examples of valid headers are listed below: