Slope 03 : (1) The variation of the terrain from the horizontal. (2) The number of feet of rise or fall, per 100 feet, measured horizontally and expressed as a percentage
Ralph W. Burklin & Robert G. Purington, Fire Terms: A Guide to Their Meaning and Use, National Protection Association, Boston, MA 1980 USA. (Guide: Meaning and Use, Nat Prot Association Fr Srvc - Amer) {457}