Alchemy TM files (.tm) are created using the Clean Up Expert, extracting all the contents of a TTK project into a multi-lingual except for the source files themselves. Often localization professionals need to amend a few entries in a .tm file for one or more languages, and rather than using the Clean Up expert again to update each language entry they may open the .tm file directly in CATALYST for edit.

Use FILE > Open > Browse  and select Alchemy Translation Memory (*.tm) in the Filetype dropdown

You will be prompted to select which language contained with the .tm file you wish to edit.

Select the language pair and click the OK button to open it.

The Languages dropdowns in the HOME ribbon are replaced by a single TM Languages dropdown selection which includes the different language pairs included in the opened Alchemy .tm file.
The Navigator window shows the .tm filename as the project title, and the current language pair opened for edit.

Once a language pair opened, all standard features of CATALYST are available. Users can translate segments in the Translator Toolbar as normal, with TM and Glossary matches available as with a TTK file.

Edit a different language pair in the opened TM by selecting it in the TM Languages dropdown in the HOME ribbon.

If you have any unsaved changes made to the current language pair, you are prompted to Save or discard those changes prior to changing the language pair.