Thanks to Dan Lusthaus and Christian Ferstl for their quick suggestions.
It seems likely to be "manuscriptis," dative plurel to agree with codicibus and thus referring to a handwritten, as opposed to a printed, volume/codex. This would fit the context at least.
best,
Matthew
Matthew Kapstein Directeur
d'études, émérite
Ecole Pratique des Hautes Etudes, Paris
Numata Visiting Professor of Buddhist Studies,
The University of Chicago
From: Dan Lusthaus <prajnapti@gmail.com> Sent: Sunday, April 5, 2020 5:11 AM To: Matthew Kapstein <mkapstei@uchicago.edu> Cc: indology@list.indology.info <INDOLOGY@list.indology.info> Subject: Re: [INDOLOGY] a puzzling codicological term