An asynchronous communications protocol that provides faster data transfer rates and better error detection than Xmodem. In particular, Zmodem supports larger block sizes and enables the transfer to resume where it left off following a communications failure.
ZMODEM
Meaning of ZMODEM in English
DAX English glossary of key connectivity terms. Английский глоссарий основных терминов по коммуникациям DAX. 2012