Variable Reference [string]

A string referencing the location of/for a value in the form of $(REFERENCE) where REFERENCE MUST start with an identifier [string] and MAY end with one or more:

• array item references
• object property references
• dir entry references

References can be used to either define or access values in the current scope.

When an op starts, it's initial scope includes:

• ./ equal to the current op directory i.e. the current op.yml can be accessed via $(./op.yml).
• ../ equal to the parent of the current op directory i.e. the current op.yml can be accessed via $(../op.yml).
• any defined inputs

note: variable references can be escaped by prefixing the [would be] variable reference with \ i.e. \\$(wouldBeVariableReference) would not be treated as a variable reference.