Is there a specific methodology or format that should be used for functional specifications?
ESCHER does not require the use of any specific standard. Tool developers are free to choose any formalism(s) that they wish as long as the fomalisms are adequate to represent the functional behavior of the tool. Examples of formalisms are: UML, sequence diagrams, interaction diagrams, use cases, Entity-Relationship (E-R) diagrams, Logical Data Model (LDM), etc.