Didger 3 was not designed to easily handle non-linear axes. You have two options when it comes to digitizing non-linear axes:

1. You can digitize it into one PJT file. You will have to digitize a section with a linear portion of the X axis, then change the project limits (to reflect the entire project), move the map, recalibrate the tablet, and digitize another section that has a linear portion of the X axis. This file will make a linear X axis, ranging across the entire X axis min/max values, and your digitized objects will be spread across it.
   
   
2. You can digitize the profile into a number of PJT files - each one containing a section of the profile that has a linear X axis.

The most recent versions of Didger can handle non-linear axes.

Updated March 20, 2014