AT&T 6300 Programmer's Manual page 63

Variable Types
SINGLE AND DOUBLE PRECISION FOR
NUMERIC CONSTANTS
Numeric constants may be either single
precision or double precision numbers. Single
precision numeric constants are stored with 7
digits of precision, and printed with up to 6
digits of precision. Double precision numeric
constants are stored with 17 digits of precision
and printed with up to 16 digits.
A single precision constant is any numeric
constant that has one of the following
characteristics:
• Seven or fewer digits and a decimal point.
• Exponential form using E.
• A trailing exclamation point
(!).
3-5