California Code of Regulations
Title 2 - Administration
Division 4.5 - Local Agency Deposit Security
Chapter 2 - Administrator of Local Agency Security
Subchapter 3 - Addition, Withdrawal and Substitution of Securities
Article 2 - Plus Substitution of Securities
Section 16003.2.1 - Plus Substitution of Securities

A depository may effect a plus substitution of securities at any time; provided, however, that no agent of depository shall release a security from a security pool pursuant to such a substitution unless a duly authorized officer thereof first endorses upon or attaches to the documents of substitution a certification that the market value of the security added to such security pool equals or exceeds the market value of the security withdrawn from such security pool.