SLED is a practical market label
SLED is commonly used as shorthand for state, local, and education public-sector markets. In practice, that can include state agencies, counties, cities, towns, school districts, public colleges and universities, authorities, and other eligible public institutions.
The term is useful for business development because these buyers often operate outside federal procurement notice systems. A company monitoring only federal opportunities can therefore miss a large category of public-sector purchasing activity.