Complex sentence: Thus, for earlier repertoire, a line marked'tenor' indicated the part's role, and not the required voice type; indeed, even as late as the eighteenth century, partbooks labelled' tenor' might contain parts for a range of voice types.
Split into simpler sentences: Thus, for earlier repertoire, a line marked'tenor' indicated the part's role, and not the required voice type. Indeed, even as late as the eighteenth century, partbooks labelled' tenor' might contain parts for a range of voice types.