Schema Input
Schema Input is an abstraction given by client which is being compiled by Fabricator into Schema - which is an internal representation of what the client expects to retrieve and how should the fabricated falsum look like.
Similarly to Schema, the Schema Input also contains declarations of fields with Value Generators assigned.
Schema Declaration
The whole process of describing the schema via Schema Input was designed with a high emphasis on it's highly declarative nature - to enable the client to be able to declare everything with somewhat static description without any functional code.
The reason for it is for example to be able to detach the schema into a separate static .json
where the application could read the schema from (as the schema input), compile it internally
and build falsa based on this model.
For this purpose, there are many string shortcuts for common stuff you can use to describe "what you want" rather than "how to achieve it".