There are four types of LOMRs:

Letter of Map Revision (LOMR)– LOMR is a revision to the currently effective FIRM which changes flood zones, delineations, and elevations by letter. This allows the Federal Emergency Management Agency (FEMA) to revise flood hazard information on a FIRM without physically revising and reprinting the entire map panel.

Conditional Letter of Map Revision (CLOMR)–A CLOMR is FEMA's comment on a proposed project within the SFHA. A CLOMR is a document that comments on whether the proposed project that would alter the SFHA on the effective FIRM meets the minimum floodplain management criteria of the NFIP and whether the analysis meets FEMA’s technical mapping standards, and, if so, what revisions will be made to the community's FIRM if the project is completed as proposed.