The International Code Council publishes the International Plumbing Code, and the International Association of Plumbing and Mechanical Officials, publishes the Uniform Plumbing Code. Both are “model” codes which are intended to be reviewed and modified by a governmental entity, before being adopted as the “Code”, and an enforceable statute.
I work for the Federal Government, and Congress adopted the International Code Council family of codes for all Federally owned buildings. With an allowance for the lead Engineer of an agency to modify the codes as necessary.
I work in Idaho, which has adopted a modified version of the International Plumbing Code, which is the Idaho Plumbing Code.
I have to install sanitary yard hydrants without weep holes to comply with the International Code, but under the Idaho Code local plumbers install the same old yard hydrant they have for the last hundred years.