 * f50 0 65 7 0 64 1.;          < linear change from value 1 to value 2
 * f52 0 65 7 0 32 1. 32 0;     < linear change from value 1 to val 2 to val 1
 * f51 0 65 7 1. 64 0;           < linear change from value 2 to value 1
 * f53 0 65 7 1. 32 0 32 1.;     < linear change from val 2 to val 1 to val 2

