In the Maine State Legislature, bills are given a label LD, short for Legislative Document. This is the most common reference for a full bill once it has been written.
The system of bill numbers is confusing because bills may have other numbers associated with them. Before a bill is written in full form by legislative staff, it is submitted to the legislature as a LR, or legislative request. LRs also have numbers used to track pending requests.
For purposes of searching on the mainelegislature.org website, it is also useful to know the HP (House Paper) or SP (Senate Paper) number of the bill, since some searches on the website require LD numbers and some searches require paper numbers.