`comint.el' revision: 1.19. `inhibit-field-text-motion' is defined to be user option, and it is reasonable. On request will describe cases when actually need to change behavior controlled by it in comint mode buffers in course of regular editing. Can not do so safely. If it is `t', `comint-previous-input', if previous command is C and current process prompt is P, expect it to create buffer text PC ^ without following newline. (Point shown as `^'.) So that C may be edited and sent. Instead, the following appears. CP ^ If execute `comint-send-input' immediately, it sends P as command. So some parts of xemacs `comint' depend on user option value.