This document tries to give a description of the .mxtsession files used in the proprietary software MobaXterm. Sadly this format, as efficient as it is, is too obscure to encourage legitimate use cases of this format as there is no public documentation available.
The software licence of MobaXterm, for both Home and Pro editions, allows to "observe, study or test the functioning of the Software in order to determine the ideas and principles which are the basis of the Software, when performing the loading, display, execution, transmission or storage of the Software" and this study has been done in full under those terms.
The studied format is the one of version 23.6: sessions last modified (but not necessarily exported) before this version will have fewer fields.