The commands created for UrbanLISP are set up in a carefully structured AutoCAD environment in which they work properly. It's not guaranteed these commands will not be interrupted during use or will be error free even though they are thoroughly tested. Those who have these commands at their disposal can use these commands "as is" with any possible faults and flaws. You are encouraged to check the results of those commands which concern important data and numbers. The user shouldn't assume all results are correct.
It's advised to use the commands in properly setup drawings. Most of these command are created in drawings using the metric system. The commands work best with properly setup blocks (in case blocks are processed). If drawing, blocks and other entities are setup properly the command works best and unexpected results are limited.
A lot of UrbanLISP commands are created to do a lot of work in one go. Weather the command is able to succeed also depends on your pc, your system. If you have to make a selection to run your command you may want to start with a small selection to see how your system reacts. The more powerful your system the bigger selections you can make.
The commands are created and tested thoroughly in the latest AutoCAD versions. There are many different CAD programs. They may respond differently to UrbanLISP commands. In the requirements section you can read what you should mind.
Tutorials for these commands show how the command should work but may be different than the actual command since the commands are frequently being updated and improved. Essential changes to a command will be registered in the development log of the command. There's no guarantee however all changes are listed here. Like the commands the website and contents are always subject for improvement. Therefore changes can be made to the website and contents at any time.