DF63

Data Storage ODS Term is the terminal-supplied value actually written to the card's on-device storage, the write-side counterpart to DF62 (covered alongside it here), which describes what the card's storage options actually are before the terminal attempts to write anything into them. Its variable length reflects that different data-storage programs write different amounts and kinds of content - there's no single universal payload this tag carries, only whatever the specific data-storage program running for this transaction defines. Because writing to on-device card storage is a state-changing operation, not merely a read, a terminal implementation handling DF63 deserves the same care already discussed for other write-capable mechanisms in this dictionary, like the Issuer Script Command (86): a write that fails partway through can leave the card's storage in a partially-updated state, which is worth accounting for in error handling rather than assuming a write either fully succeeds or has no effect at all. See EMV Contactless Book C-2.