1 byte of data is read out from the data
buffer and written into the LS area. That means only the lowest 8
bits (1 byte) of the LS area will be used. The significant 8 bits
(1 byte) will be cleared with "0".
When the specified value [source offset
value + number of characters to be copied] is greater than the data
buffer size, error Number 3 (string extraction error) of the string
error status [e: STR_ERR_STAT] is issued.
The processing is terminated when an error
occurs and returns to the beginning of the Main function. (If the
command comes while a function is running, it returns to the line
that called that function.)
