| 
Item
 | 
Actual
 | 
Minimum
 | 
 
 | 
| 
 
 | 
 
 | 
Acceptable
 | 
 
 | 
| 
nesting levels of compound statements, iteration
control structures, and selection control structures.
 | 
>=256
 | 
15
 | 
nesting levels of conditional inclusion
 | 
| 
>=32
 | 
8
 | 
 
 | 
pointer, array, and function declarators (in any combinations)
modifying an arithmetic, a structure, a union,
or an incomplete type in a declaration
 | 
| 
>=32
 | 
12
 | 
 
 | 
declarators nested by parentheses within a full declarator
 | 
| 
>=32
 | 
12
 | 
 
 | 
expressions nested by parentheses within a full expression
 | 
| 
>=128
 | 
32
 | 
 
 | 
significant initial characters in an internal identifier or
a macro name
 | 
| 
>=1024
 | 
31
 | 
 
 | 
significant initial characters in an external identifier
 | 
| 
>=1024
 | 
6
 | 
 
 | 
external identifiers in one translation unit
 | 
| 
>=1024
 | 
511
 | 
 
 | 
identifiers with block scope declared in one block
 | 
| 
>=2048
 | 
127
 | 
 
 | 
macro identifiers simultaneously defined in one translation unit
 | 
| 
>=4096
 | 
1024
 | 
 
 | 
parameters in one function definition
 | 
| 
>=256
 | 
31
 | 
 
 | 
arguments in one function call
 | 
| 
>=256
 | 
31
 | 
 
 | 
parameters in one macro definition
 | 
| 
>=128
 | 
31
 | 
 
 | 
arguments in one macro invocation
 | 
| 
>=128
 | 
31
 | 
 
 | 
characters in a logical source line
 | 
| 
>=4096
 | 
509
 | 
 
 | 
characters in a character string literal
or wide string literal (after concatenation)
 | 
| 
>=4096
 | 
509
 | 
 
 | 
bytes in an object (in a hosted environment)
 | 
| 
>=65535
 | 
32767
 | 
 
 | 
nesting levels for #include'd files
 | 
| 
>=16
 | 
8
 | 
 
 | 
case labels for a switch statement (excluding those for any nested
switch statements)
 | 
| 
unlimited
 | 
257
 | 
 
 | 
members in a single structure or union
 | 
| 
>=512
 | 
127
 | 
 
 | 
enumeration constants in a single enumeration
 | 
| 
>=512
 | 
127
 | 
 
 | 
levels of nested structure or union definitions in
a single struct-declaration-list
 | 
| 
>=64
 | 
15
 | 
 
 | 
functions that can be registered by atexit().
 | 
| 
37
 | 
32
 | 
 
 |