Working outside
Often TMSs are based on a subscription model in which you pay for the number of concurrent users, i.e. people that use the tool at the same time. As a result, it is good if the TMS offered the possibility for the vendor to work in another CAT tool.
It is possible to work outside a TMS by downloading a package with all language resources. Some translation vendors may not like, or are not familiar with, the TMS that you have bought so this option is also a nice alternative.
XTM offers an opportunity to download an xliff file from the Offline translation column.
After translation in another CAT tool, a vendor should import the xliff file back to XTM by clicking Upload file in the Offline translation column.
The translation memory is updated automatically and it is possible to generate the target file from XTM.