Jenn, > 1) What type of data are you currently putting in the top-level <extension> element? We use the <extension> element for local holdings info and for non-roman data. If a MARC record contains 880 fields, then we create a second <mods> element using the 880s and stick it in <extension>. You can see an example here: http://copac.ac.uk/search?ti=Qian+gu+zhi+mi&rn=1&format=XML+-+MODS > 2) Do you have specific cases in which it would be helpful to you to have <extension> inside a specific MODS element rather than at the top level to convey additional semantics? No. > 3) Have you made changes to the MODS schema locally to allow for additional elements not in the MODS schema? No. Regards, Ashley. -- Ashley Sanders [log in to unmask] Copac http://copac.ac.uk A Mimas service funded by JISC