==== Question A. Combining / overriding / extended syntax ====
A number of options for allowing re-transposition have been discussed, mostly relating to how the modifiers in a ''K:'' or ''V:'' field interact with each other (either combining or overriding).

There are five choices.

The following (nonsensical) example is used in each choice to illustrate what effect the interaction has:
  K:C instrument=_E;abc@written shift=CG clef=treble clef=alto octave=1 octave=1
which, when you replace the ''instrument'' and ''shift'' shorthands, resolves to
  K:C shift-score=cc shift-sound=c_E shift-score=CG shift-sound=CG clef=treble clef=alto octave=1 octave=1

  - All modifiers in a K: or V: field combine.\\ \\ This means that modifiers such as ''instrument='' and ''shift='' may be combined (by resolving to their ''shift-score='' & ''shift-sound='' equivalents). Although nonsensical, repeated combinable modifiers (e.g. ''stafflines='' and ''octave='') are legal and add their effects.\\ \\ This rule does not apply to non-combinable modifiers such as ''clef'' and accidentals (K: field only) and in these cases the last one overrides any previous modifier of the same type (software may issue a non-fatal error message).\\ \\ The example resolves to \\ <code>K:C shift-score=CG shift-sound=c_B clef=alto octave=2</code>\\
  - All modifiers in a K: or V: field combine but may not be repeated.\\ \\ This means that modifiers such as ''instrument='' and ''shift='' may be combined (by resolving to their ''shift-score='' & ''shift-sound='' equivalents).\\ \\ In the case of repeated modifiers, the last one overrides any previous modifier of the same type (software may issue a non-fatal error message). In this context ''instrument='' and ''shift='' are not regarded as repeats of ''shift-score='' and ''shift-sound='' even though they are defined in terms of them.\\ \\ The example resolves to\\ <code>K:C shift-score=CG shift-sound=c_B clef=alto octave=1</code>\\
  - All ''shift-score='', ''shift-sound='', ''shift='' and ''instrument='' modifiers in a K: or V: field combine.\\ \\ To combine them, resolve to their ''shift-score='' & ''shift-sound='' equivalents.\\ \\ In the case of any other repeated modifiers, the last one overrides any previous modifier of the same type (software may issue a non-fatal error message).\\ \\ The example resolves to\\ <code>K:C shift-score=CG shift-sound=c_B clef=alto octave=1</code>\\
  - All ''shift-score='', ''shift-sound='', ''shift='' and ''instrument='' modfiers  in a K: or V: field combine but may not be repeated.\\ \\ To combine them, resolve to their ''shift-score='' & ''shift-sound='' equivalents.\\ \\ In the case of repeated modifiers, the last one overrides any previous modifier of the same type (software may issue a non-fatal error message). In this context ''instrument='' and ''shift='' are not regarded as repeats of ''shift-score='' and ''shift-sound='' even though they are defined in terms of them.\\ \\ The example resolves to\\ <code>K:C shift-score=CG shift-sound=c_B clef=alto octave=1</code>\\
  - All modifiers in a K: or V: field override. The ''instrument=<note>;abc@concert'' and ''instrument=<note>;abc@written'' modifier may optionally include an additional transposition.\\ \\ ''instrument=<note>;abc@concert;+<note1><note2>'' is "shorthand" for ''shift-score=<note1><note2>+<note>c shift-sound=<note1><note2>''\\ ''instrument=<note>;abc@written;+<note1><note2>'' is "shorthand" for ''shift-score=<note1><note2> shift-sound=<note1>note2>+c<note>''\\ \\ Here the ''+'' adds the two transposition intervals together.\\ \\ In the case of repeated modifiers, the last one overrides any previous modifier of the same type (software may issue a non-fatal error message). In this context ''instrument='' and ''shift='' should be resolved to ''shift-score='' and ''shift-sound='' before overriding is evaluated.\\ \\ The example resolves to\\ <code>K:C shift-score=CG shift-sound=CG clef=treble octave=1</code> \\ To achieve the same as combining syntaxes, the example may be rewritten\\ <code>K:C instrument=_E;abc@written;+CG clef=treble clef=alto octave=1 octave=1</code> which resolves to\\ <code>K:C shift-score=CG shift-sound=c_B clef=alto octave=1</code>\\

==== Question B. Instrument modifier wording ====
A number of options have been proposed for the wording to represent "the abc is encoded at concert/written pitch for an instrument in <note>".

The following express those options for an instrument in low C:

  - ''instrument=C;concert-abc'' \\ ''instrument=C;written-abc''\\
  - ''instrument=C;abc=concert'' \\ ''instrument=C;abc=written''\\
  - ''instrument=C;abc@concert'' \\ ''instrument=C;abc@written''\\
  - ''instrument=C;concert'' \\ ''instrument=C;written''\\
  - ''instrument=C;abc-as-sounded'' \\ ''instrument=C;abc-as-written''\\
  - ''instrument=C/abc-sound'' \\ ''instrument=C/abc-score''\\
  - ''instrument-concert=C'' \\ ''instrument-written=C''\\
  - ''concert-abc:instrument=C'' \\ ''written-abc:instrument=C''\\
  - ''shift=instrument-in:C/abc@sound'' \\ ''shift=instrument-in:C/abc@score''\\

In most cases these options could have a shorthand (e.g. in the case of 1, 2, and 3 it could be ''instrument=C;concert'' / ''instrument=C;written'') but we will decide on that later.