C Standard Library: 11 Implementation-defined Limits: and

The header <limits.h> defines constants for the sizes of integral types.
The values below are acceptable minimum magnitudes; larger values may be
used.

CHAR_BIT 8 bits in a char
CHAR_MAX UCHAR_MAX or
SCHAR_MAX maximum value of char
CHAR_MIN 0 or SCHAR_MIN maximum value of char
INT_MAX 32767 maximum value of int
INT_MIN -32767 minimum value of int
LONG_MAX 2147483647 maximum value of long
LONG_MIN -2147483647 minimum value of long
SCHAR_MAX +127 maximum value of signed char
SCHAR_MIN -127 minimum value of signed char
SHRT_MAX +32767 maximum value of short
SHRT_MIN -32767 minimum value of short
UCHAR_MAX 255 maximum value of unsigned char
UINT_MAX 65535 maximum value of unsigned int
ULONG_MAX 4294967295 maximum value of unsigned long
USHRT_MAX 65535 maximum value of unsigned short

The names in the table below, a subset of <float.h>, are constants related
to floating-point arithmetic. When a value is given, it represents the
minimum magnitude for the corresponding quantity. Each implementation
defines appropriate values.

FLT_RADIX 2 radix of exponent, representation, e.g., 2, 16
FLT_ROUNDS floating-point rounding mode for addition
FLT_DIG 6 decimal digits of precision
FLT_EPSILON 1E-5 smallest number x such that 1.0+x != 1.0
FLT_MANT_DIG number of base FLT_RADIX in mantissa
FLT_MAX 1E+37 maximum floating-point number
FLT_MAX_EXP maximum n such that FLT_RADIXn-1 is representable
FLT_MIN 1E-37 minimum normalized floating-point number
FLT_MIN_EXP minimum n such that 10n is a normalized number
DBL_DIG 10 decimal digits of precision
DBL_EPSILON 1E-9 smallest number x such that 1.0+x != 1.0
DBL_MANT_DIG number of base FLT_RADIX in mantissa

DBL_MAX 1E+37 maximum double floating-point number
DBL_MAX_EXP maximum n such that FLT_RADIXn-1 is representable
DBL_MIN 1E-37 minimum normalized double floating-point number
DBL_MIN_EXP minimum n such that 10n is a normalized number