The .justm format is used to save a JustMeasure project.
A project can contain source images, tabs, calibrations, helper geometry, measurements and other settings required to continue working.
Saving
Save the project regularly, just as you would save a working file in another professional application.
Opening
A .justm file can be loaded back into JustMeasure so you can continue working with the preserved project state.
The format is versioned so that older projects can be migrated in a controlled way as the application evolves.