Spellcant

Spellcant is a written magical code used by spellcasters in order to hide their writings through the using a specific and consistent form of the spell Illusory Script. It was created as a direct to the invention of the Mass Printing Press. What sets Spellcant apart from just being simply Illusory Script is how it appears to spellcasters vs non-spellcasters. When read by spellcaster, the obscured text is made visible, just like a regular Illusory Script. When a non-spellcaster reads it however, it appears as 'Small Meals with Big Taste' by Fenkasys Carwyse . Nearly all spellbooks, grimioires, and arcane tomes for the last 1000 years in Edren are wrote in this code, to keep their knowledege out of the hands of The Engineers.
Spellcant is at its core simply using the spell Illusory Script, and declaring 'spellcasters' as the intended audience, and 'non-spellcasters' as the excluded audience. While this illusion is normally performed by a member of The Mages, any spellcaster may read it; however, this spell is intended to exclude The Engineers. While many argue this is enough to be considered spellcant (as a non-spellcaster is excluded), some argue without the touch of making it always appear as 'Small Meals with Big Taste', it is not 'true Spellcant'.
The reason for including Carwyse's novel as the illusion dates back to her invention of the Mass Printing Press. After its invention in 162, some of The Mages became incredibly paranoid that their writings would be mass produced by The Engineers, and a way to limit their magic might be discovered. In response, The Mages moved to have all future writings be done in Spellcant, and all previous books be converted and the originals burned. This was a highly controversial decision, as many believe many original texts, spells, and research were lost in these burnings. The choice use 'Small Meals with Big Taste' was a direct jab at Carwyse and her invention of the mass printing press. 
There was never any strong documentation that The Engineers planned to mass produce any spellbook, but the fear was vey real amongst The Mages of the time, and that tradition has continued to this day. Nearly all spellbooks are wrote in this method to this day, to make it difficult for The Engineers from using their research to fight against magic.