Joined: 15 Feb 2005 Posts: 7129 Location: San Jose, CA
A 3-byte ZD value looks like this in hex:
zdzdsd
where z is the zone (usually F), d is a digit (0-9) and s is the sign.
Normally, for ZD fields, the sign is C or F for positive and D for negative. Both C and F are valid signs for positive ZD values. If the F sign is used for positive values, then the value is "displayable" - for example, +123 would be X'F1F2F3' = '123'. If the C sign is used for positive values, then value is not displayable - for example, +123 would be X'F1F2C3' = '12C'.