Q: Treatment of Designation and Title in Text I work at a company that publishes standards. These publications have a designation and a title.  For example, the designation might be "Standard 100."  The title might be something like "Machines Handbook."
Most (but not all) of our publications punctuate the in-text reference as follows:
Standard 100, Machines Handbook
I was wondering if it is more proper to treat the title as a subtitle and punctuate it as follows, with AP guidelines concerning reference material in mind:
Standard 100: Machines Handbook
I've been looking at all my online resources, and none seem to take this specific case into account when addressing title punctuation. My ancient copies of Rude's Technical Editing and  Reisman's A Style Manual for Technical Writers & Editors are not helpful, either. ISO appears to use the comma/italicized style. It would be nice to hear how professional editors would handle this if they were in charge of setting a standard for style.

A: I'd first look for examples of similar styling, as you've done. You might find more examples if you think of the standard number and title as being like the volume number and title of a book in a series, and see how different style guides handle that. MLA and Chicago styles separate the volume number and its title with a comma; others use a colon.  
Since most of your company's publications use the comma style, I'm guessing you'd need to make a case for changing it, and that might be hard. The comma style has two things in its favor: it's what ISO uses, so it already conforms to a reputable standard, and it's what your company uses, so it's consistent. I prefer it, too, because it seems odd to treat the title as a subtitle when it's not.
