I need help with settlement_plan.txt

Hasn't anybody written a settlement_plan tutorial? If the answer is no, then please give me the link, if i'm right then... I've got some questions for modders who know how to mess with this file.
1.How does it influence the other files? and what other files are influenced if i change it? what other files i might need changing if i change this?
2.How do I MOD it, please give me some synthax explanations, and tell me what do i need to know to move buildings around and stuff like this.
Thanks a lot!