Guy explains quite well, in his post above.
If you do not know what an “API” is, you can read the definition at Wikipedia:
If you are interested in Microsoft Visio, you’ll need to do your own research, and try it out to understand what features might also work well in LayOut. (No there is no plugging them together! We would just like LayOut to have some of the features like an API, attributes, gluepoints, smartshapes, etc.)
Related threads: