The attached file shows several spatial addition problems which include a single variable. Both the 1972 and Provisional lessons clearly state that no numeric indicator is used in spatial math which is aligned for computation. But they never actually say in words or examples that the ELI is not used. I assumed it was not used. Is there somewhere that this is actually stated either in words or examples? Another transcriber used a spatial fraction example to convince himself we would use the ELI in the problems attached. Perhaps I made the incorrect assumption.
I would look to both the example under Nemeth Code section 178.g and the text of Nemeth Code section 27.g for reasons to *not* use the English Letter Indicator in problems involving variables arranged spatially for calculation. That still doesn’t give you language that says not to use the ELI for variables in a problem arranged spatially, but I think those pieces effectively define the *lack* of a requirement for ELIs in problems arranged spatially for calculation.
As always, thank you for the question, and please do not hesitate to post follow-up questions/concerns.