This format is useful
in operating environments where a float value is not the same as a
truncated double. Values that are written by FLOAT4. typically are
values that are meant to be read by some other external program that
runs in your operating environment and that expects these single-precision
values.
Note: If the value that is to be
formatted is a missing value, or if it is out-of-range for a native
single-precision, floating-point value, a single-precision value of
zero is generated.
On IBM mainframe systems,
a four-byte floating-point number is the same as a truncated eight-byte
floating-point number. However, in operating environments using the
IEEE floating-point standard, such as IBM PC-based operating environments
and most UNIX operating environments, a four-byte floating-point number
is not the same as a truncated double. Hence, the RB4. format does
not produce the same results as the FLOAT4. format. Floating-point
representations other than IEEE might have this same characteristic.