Babylon bgl files are available for free in many languages and domains, so they can be a valuable resource. The converter allows to read (some of) them. They are monolingual (term + definition) or bilingual (term + translation). There are a few problems that distinguish them from other formats:

Undocumented binary format

The file format has partially been reverse engineered to allow reading data. This process includes a lot of guesswork and ignoring of unknown parts. Therefore, while most tested files sort of work, some produce unusable results. There is also no guarantee that Babylon will keep the format, it could change any day.

HTML content 

The format is designed to be displayed in Babylon, which allows HTML formatting. Therefore, quite a few glossaries contain rich formatting that makes is impossible to automatically detect relevant content. Some cleanup is performed, but it is not comprehensive. If the result contains unwanted markup, I recommend to first convert to txt, and see if you can repair it in that format; sometimes a simple search and replace is all that is required. Convert the cleaned txt to sdltb in a second step.   

Use as an output format

You can't create bgl files directly. The format uses unknown headers and checksums that make it impossible to do that. A workaround is the free Babylon Glossary Builder:

It creates bgl files from spreadsheets. So you can use the Glossary Converter to create a bilingual xlsx file from your termbase (if you have more than 2 languages, filter all but source and target), and then use the builder to convert them to bgl and import them into your Babylon repository. 

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