Variable length refers to the number of bytes used to store a variable's values in a SAS data set.

The number of bytes for variables containing characters (literals) is the maximum width number of characters in a variable. Regardless of the operating system (Windows, Unix, Linux, VMS), each byte represents a single character.

The number of bytes for variables containing numeric data determines the precision with which the numbers are stored. Operating systems differ in ways in which numeric data are stored.

Significant digits and largest integer by length for SAS variables under Windows, Linux, and Unix

Length in bytes	Largest integer represented exactly	Exponential notation	Significant digits retained
3	8,192	2^13	3
4	2,097,152	2^21	6
5	536,870,912	2^29	8
6	137,438,953,472	2^37	11
7	35,184,372,088,832	2^45	13
8	9,007,199,254,740,992	2^53	15

For OpenVMS on Alpha, the architecture defines the largest integer as one less than Windows, Unix, and Linux.