NOT.2:4.4 - Define the permitted connections between components

Specify which component places can be connected and what the connection means for forming the expression. If a connection passes a result to an operand, include the operand’s position or role as well as its accepted kind. Two inputs of the same kind may still be ordered.

Construct the compound expression and determine its remaining external inputs and outputs. Check each newly connected boundary; an unconnected required input remains an input to be supplied. If the scheme permits shared values, show how repeated references obtain that value. If it describes resources whose copying requires an operation, include that operation rather than deriving copying from a forked line alone.

A connection that forms a cycle needs a rule admitting and interpreting that cycle. Depending on the practice, it might describe an equation, feedback through time or a repeated computation. Choose the intended construction before using one picture for these different operations. NOT.3 develops its interpretation, and CMP.12 supplies an effective evaluator when one is required.

Formation rules establish a permitted expression. Whether its described mathematical construction exists, its algorithm terminates or its physical realization works remains a question for the corresponding methods. The rules should expose the information those questions need.