Mono is a platform for running and developing applications based on the ecma/iso standards. mono is an open source effort led by novell. mono provides a complete clr (common language runtime) including compiler and runtime, which can produce and execute cil (common intermediate language) bytecode (aka assemblies), and a class library.

this package contains various mono.data.* libraries for cli 2.0 that allow to use different tds-based databases:
- mono.data
- mono.data.tdsclient:
generic tds provider (tds 4.2 by default) for older versions of sybase and
microsoft sql servers.
- mono.data.sybaseclient:
provider for sybase sql servers (tds 5.0)
if you are looking for a current microsoft sql server library then you want to check the libmono-system-data2.0-cil package which contains system.data.sqlclient.

for more information about mono.data and tds see: http://www.mono-project.com/tds_providers