A behavior support plan is the document that tells staff how to support a person around a specific behavior. It usually describes what the behavior looks like, what tends to come before it, and what the people on the shift are supposed to do. Agencies file it with the individual support plan. The approach it is supposed to reflect is positive behavior support: change the conditions, teach a skill, do not lead with punishment.
The plan is only as good as the shift. A direct support professional who was not trained on it will improvise. A plan written for a day program and handed to overnight residential staff may describe a building those staff never work in. When incidents rise, the useful question is whether the plan matches the hour it failed in.
Some plans limit rights. They may restrict access to something, require extra supervision, or, under a separate state rule, allow a restrictive procedure. Those limits are supposed to go through extra review. Many states use a human rights committee or a similar body. The existence of a committee is not a definition of good support. It is a procedural check the state required because restriction is a rights issue, not a staff preference.
This page does not describe restraints, holds, or how to respond in a crisis. Those steps, where a state allows them at all, live in regulation and in a plan specific to one person. Quoting them in a glossary would pretend they are general technique. They are not.
Readers will see BSP, behavior plan, and positive behavior support plan used for the same attachment. Ask who wrote it, who was trained, and whether any restriction in it was reviewed. Those three facts tell you more than the title.