Expression Calculation: expression = formula?

Greetings!

I am trying to work out a normative statement from current 2.2 
Expression Calculation.

I stumble over sentences like: "Any formula is an expression that 
produces a result."

So, is an expression that doesn't produce a result not a formula?

Or are the terms expression and formula meant to be interchangeable in 
all cases?

My operating assumption is that they are equivalent.

So, why not just pick one? I am indifferent to which one.

I have several questions but will separate them for clarity's sake.

Hope everyone is having a great weekend!

Patrick

-- 
Patrick Durusau

Chair, V1 - US TAG to JTC 1/SC 34
Convener, JTC 1/SC 34/WG 3 (Topic Maps)
Editor, OpenDocument Format TC (OASIS), Project Editor ISO/IEC 26300
Co-Editor, ISO/IEC 13250-1, 13250-5 (Topic Maps)