This definition is adapted from the Geospatial integrity of geoscience software (GIGS) documentation, part 1: Guidlines:
As the values of coordinate transformation parameters are based on sample data, there may be multiple ways of transforming coordinates from one CRS to another:
Some software resolves the multiplicity problem by associating one coordinate transformation only with each CRS. The relevant coordinate transformation is even treated as part of the definition of the CRS. This solution to the problem of multiplicity is referred to as early-binding, as it binds a coordinate transformation to the CRS before it is associated with any geospatial data.
Late-binding software solutions to the multiplicity problem will only require the specification of a coordinate transformation at the time the coordinates are required to be transformed.