AutoLISP programs can be used in an AutoCAD release that supports a language other than the original language the program was developed for.
The standard AutoCAD commands and keywords used in an AutoLISP program can be automatically translated if you precede each command or keyword with an underscore (_).
(command "_line" pt1 pt2 pt3 "_c")
If you are using the dot prefix (to avoid using redefined commands), you can place the dot and underscore in either order. Both "._line" and "_.line" are valid.