Dictionary:
the principle or practice of submitting to popular vote a measure passed on or proposed by a legislative body or by popular initiative
https://www.merriam-webster.com/dictionary/referendum
From The Maryland Constitution:
SECTION 1. (a) The people reserve to themselves power known as The Referendum, by petition to have submitted to the registered voters of the State, to approve or reject at the polls, any Act, or part of any Act of the General Assembly, if approved by the Governor, or, if passed by the General Assembly over the veto of the Governor;
The power of referendum is found in the charters of each charter county in the state, except Baltimore City.
The charter based authorization of referendum includes several key elements.
Scope of Referendum: This explains what laws passed by the county are subject to the referendum process. While there is some difference, common exclusions include: appropriations, taxation, council redistricting, school construction.
Amount of Petition Signatures Required to Send an Act to Voters: Each charter specifies a number of voters required to sign a petition in order to invoke the referendum. In most cases this is a percentage, though in some cases it is an amount. These clauses also specify what it is a percentage of. Charters calculate their signature threshold based on percentage of voters in a given election, or percentage of registered voters.
In the tables below the amount of valid signatures is represented in the “Signature Threshold” field, and the “Percentage Of” field shows what it is calculated against.