By A-R's house editors

Ornaments (such as trills, turns, and mordents) should as a rule be reproduced exactly as they appear in the source. If it can be determined that variant forms of a symbol do not indicate distinctions of interpretation or that different symbols have exactly the same meaning, however, these should be regularized with the policy described and justified in the editorial methods. Ornaments are placed above the staff unless voices with opposing stems share a staff, in which case the ornaments go at the stem end (see figure 1). Added ornaments are placed in brackets.

Figure 1. From Etienne Ozi, Six duos pour deux bassons, ed. Harold E. Griswold (C059)
Figure 1

Questions of interpretation and suggested realizations may be presented in the notes on performance in the introduction (perhaps with notated examples). 

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