What is the PARAMETER["Height"] in CRS?

LorenDawe

A client has provided a PRJ file (attached) that contains a "Height" parameter:

Well-known text PROJCS["PTL1_Buenaventura",GEOGCS["GCS_MAGNA",DATUM["D_MAGNA",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["IGAC_Plano_Cartesiano"],PARAMETER["False_Easting",100000.0],PARAMETER["False_Northing",100000.0],PARAMETER["Longitude_Of_Center",-76.85094890833329],PARAMETER["Latitude_Of_Center",3.85779813888889],PARAMETER["Height",315.0],UNIT["Meter",1.0]]

I have three questions regarding this:

1 - What does this refer to?

2 - Does this parameter affect the horizontal coordinates in a transformation/re-projection?

3 - Can this be applied using PROJ4? If so, how?

Thanks in Advance,

Loren.