Use of LC xlink instead of w3c xlink fails in mixed validation. Mixup/clashes in schema definitions.

[klindt]

ALTO (also true for MODS, METS and EAD) uses a LoC version of xlink.xsd (http://www.loc.gov/standards/xlink/xlink.xsd) but with a w3c namespace (https://www.w3.org/1999/xlink.xsd). When validating mixed xml we prefer to use the w3c version of the schema but this fails some cases of LoC standards and using the LoC version does'nt validate other schemas.

Could ALTO be updated to either use w3c xlink.xsd or replace xlink: with something like simpleLink like in the PREMIS3 schema?

Old discussion here: https://listserv.loc.gov/cgi-bin/wa?A2=ind1110&L=MODS&D=0&P=9585