Misleads the readerCheckable from the score alone
An instrument name that implies transposition, left at the field's 0 default, silently produces an un-transposed part
When an instrument's name unambiguously implies a transposing instrument (e.g. 'Clarinet in Bb', 'Horn in F', 'Trumpet in Bb', 'Alto Saxophone', 'English Horn'), its `transposition` field should be auto-inferred from that name exactly as `clef` already is — leaving it at its 0 default silently produces a part written and sounding at the same pitch, which is wrong for every one of those instruments. This is a distinct, arguably higher-risk fault than supplying the wrong SIGN on an explicit value (transposition-field-sign-convention-mismatch): it requires no incorrect value at all, only silence — the schema's own default path, and therefore the path of least resistance for an agent author who does not already know the instrument transposes.