Hello
Further to a question at MUUG Nov. RoundTable, about the nature of the data exchanged when we (or xorgconfig does a) "probe for type of monitor"
VESA-compliant video cards (post'94) have a function to ask an attached monitor its EDID info.
This handy VESA function is nicely explained by: http://en.wikipedia.org/wiki/Extended_display_identification_data
Unfortunately, modern flat displays and TVs are not well represented under EDID paradigms.
EDID data for a monitor is programmed into a serial (usu.i2c friendly) PROM at manufacture. This self-descriptor keeps enough data to be capable of being "verbose" when queried; e.g: Mfg ID, Prod ID, SerNum, WkMfg, YrMfg, HSync, VSync, Resolution (EDID "thinks" this geometry must be multiple-of-8)
However, the recent Linux version of _ddc-control_ includes a separate XML-formatted db, which has been updated as recently as 2006-10.
Haven't read inside latest _ddc-control_: http://sourceforge.net/project/showfiles.php?group_id=117933 -but I suspect its useage is de-volving (at least for LCD and 'wide' displays) to a terse query from monitor, getting just the Maker, Model, and then using those to do a lookup in the XML-db.
Another Linux tool _read-edid_ also reads info from monitor: http://freshmeat.net/projects/read-edid/
Assembler and x86 machine language fans will enjoy this 2003-04 kernel snippet- http://lwn.net/Articles/27597/
smiles, John D