DDCHB 
Calculates the difference (with rollover) between the current reading and last reading.

SYNTAX:

DDCHB(Cx, Optional Rollover)
where :
Cx is a conditional variable x 

NOTES:

Typically used with a daily detail variable (Hourly, 15 Minute...).  The function will search the for last reading in the current day, previous day, and two days ago before giving up. If rollover is omitted, rollover is assumed at the next power of 10.

EXAMPLES:

V65 = DDCHB(C64)