AVLMAP is a key:data pair data mapping (associative array) library for C programming based on AVL balanced binary trees. Added features include ordered data retrieval forward or reverse, support for optional duplicate keys (e.g. an extra linked list not needed), and the ability to find the nearest member if an exact match isn't available. Both key and data types may be selected from a choice of C data types including string and array variations. One mapping always has one key type, but data types may be mixed within a mapping.