Sign on the dotted line informal verb phrase
To make an official agreement on doing something especially by signing the contract
I haven't signed on the dotted line because I am not satisfied with some rules.
To make sure the cooperation between two companies, before we sign on the dotted line, we should carefully read the rules on the contract.
When you officially work for the company, you have to sign on the dotted line.
To sign a document that one loses or gives up his or her property or legal rights
This figure of speech alludes to the broken line customarily showing up at the foot of a legitimate report, showing the put for one's signature. It came from the early 1900s.