These are all from non-technical material, EBAE. I'm confused about when to use the letter indicator following the hyphen. None of these would be misread if it wasn't included, but the rule seems to be different for each instance.
1-MCP (I think I'm required to include the letter indicator according to EBAE Rule II.12.a.)
1-Methylcyclopropene (I think this does not need the letter indicator because it is a word that would not be misunderstood, but I'm not sure where it says that in EBAE.)
1-800-MEDICARE (I think I'm required to include the letter indicator according to EBAE Rule VI.27.f.)
Any help clarifying this would really be appreciated.