Clarify meaning of 'guitar'

[TimCrawford]

In various places throughout the tablature MEI docs there is reference to 'guitar', almost exclusively referring to some generic 'modern' form of the instrument for which there is a large amount of tablature in 'internet' (ASCII) or proprietary formats. As acknowledged in the encoding details, this in turn may be an acoustic or an electric instrument. That's not the issue here.

There is also a large repertory of historical guitar tablatures, which have their own special features, including the use of 'alfabetto' notation, in which a single large capital letter is assigned to each of a set of chord-shapes rather than individual notes; sometimes this is combined with 'standard' tablature in a number of ways. These cannot be encoded in the same way as the 'guitar' tab referred to above.

So 'guitar' tablature is not standard for all time. Similarly, in MEI, the shorthand 'guitar' is not a sufficient specification of a tuning for all guitars (though as a default the modern 6-string guitar's e' b' g d a E is reasonable).

[DILewis]

I think this raises multiple issues.

• Notation type. Our proposal is currently tab.guitar for modern guitar tab. That could change to be clearer, if that would help. I don't know enough about alfabetto to know whether it'd be a different notationtype or a set of symbols included in another notation (as classical guitar music would be – CMN, with some extras)
• Tuning/instrumental setup. Our proposal was to have a shortcut for standard six-string tuning as tuning.standard="guitar", with other tunings including tuning.standard="guitar.drop.D". We have longer ways of listing rarer tuning. Again, names can change if it clarifies things.
• Specifying the instrument. This is something we haven't addressed, because it's kind of core MEI to specify an instrument (or should be). You can link to an external fixed vocabulary, I think, but I have no experience with that.