HP C A.06.05 Reference Manual

Data Types and Declarations
Storage-Class Specifiers
Chapter 3 39
If no storage class is specified and the declaration appears in a block, the compiler defaults
the storage duration for an object to automatic. If the declaration of an identifier for a function
has no storage-class specifier, its linkage is determined exactly as if it were declared with the
extern storage-class specifier.
If no storage class is specified and the declaration appears outside of a function, the compiler
treats it as an externally visible object with static duration.