[wxMaxima] File Format .wxm - wxMaxima-developers/wxmaxima GitHub Wiki
The .wxm files contain the worksheet except Maxima’s output.
On Maxima versions >5.38 they can be read using Maxima’s load() function just as .mac files can be.
With this plain-text format it sometimes is unavoidable that worksheets that use new features are not downwards-compatible with older versions of wxMaxima.