Steren CAL-150 Instructivo De Uso página 244

Counting jumps
This option allows for the increase or decrease of a value in
a specifi c memory slot once. If the value is equal to zero,
the following command will be omitted, and the following
command to be executed will be " : " or
The "Isz" command is used for increasing the value in the
memory by 1 and deciding the following execution. The
"Dsz" command is used for decreasing the value in the
memory by 1 and deciding the following execution.