The Reticulum is a large data network, linking almost all syntactic devices on Arbre. It is colloquially referred to as the Ret.
When written with a lowercase R, "reticulum" refers simply to any set of interconnected networks of syndevs (an individual network, such as one you might have in your home or office, is referred to simply as a "reticule"). When written with a capital R, "Reticulum" refers to the world-wide network composed of every lowercase-r reticulum on Arbre.
The Ret was at one time flooded with 'crap', seemingly correct documents and other media with slight errors in them. The Ita devised a method to distinguish legit documents from tarnished ones.
It is likely that in modern Orth, these words are used exclusively to refer to networks of syntactic devices and the older senses of "reticule" referring to something grid- or netlike (given in the Dictionary excerpt at the beginning of Part 7, "Feral") are largely forgotten. The word "network" appears frequently throughout the text, but with one exception, it always refers to something other than a syndev network.