[Technology] Standard Construction Template

[Exthalion]

I had originally assumed that an STC represented a sort of compendium of human knowledge, containing not only whatever would be necessary for a colony to function but all other technology and basic designs of humanity. However after reading Dark Adeptus of the Grey Knights Trilogy it would seem that each STC only contains the plans for a single constructs.

The question I would like to ask is this:

Are STC's one design specific (in which case why are they all that rare or complicated) or do they in fact contain a complete set of designs?
.          As a corollary, why would one design be favored over another and what would the implications be for the Imperium or the Adeptus Mechanium if a pure STC would add little to the total of human knowledge?

Thank you for our time and patience in reading this.

[Dragon Lord]

I believe that the difference is whether you are refering to The STC (probably more correctly The STC System) or an STC.  A singular Standard Template Construct is in my inferrence a design/pattern for making a specific technological item.  The STC System is the complete collection/encyclopedia of these individual construct patterns that, at the time of its creation amounted to pretty much a complete compendium of human technological knowledge.
No complete STC System has ever been recovered, however numerous STC designs have been, which you can consider as the individual pages of an encyclopedia being much more lasting and likely to survive than the book in which they are bound.  So the answer to your question then is both, there is a complete overarching STC System that is the technological encyclopedia and there are STC designs that are derived from it.

Some of the most common items in the Imperium, e.g. lasguns, rhinos and chimeras are based on STC designs, however finding a new piece of STC data is rare and highly prized by the Adeptus Mechanicus as STC designs are generally superior to 'modern' designs (hence why the above common items are made using the STC data).