to use the RwL it is necessary to observe the job and record the object weight, posture at the beginning [origin] and end [destination] of lift, the lift frequency, lift duration, and grip. These variables should be measured as accurately as possible while observing the job, however, it is often necessary to estimate some variables and it is wise to record the job on videotape and/or with still photographs for future reference. Definitions of these variables are noted below :