The following table list all valid values that can be used in an equivalent class expression [=class=]:

SymbolicCharacter
NUL\x00
SOH\x01
STX\x02
ETX\x03
EOT\x04
ENQ\x05
ACK\x06
alert\x07
backspace\x08
tab\t
newline\n
vertical-tab\v
form-feed\f
carriage-return\r
SO\xE
SI\xF
DLE\x10
DC1\x11
DC2\x12
DC3\x13
DC4\x14
NAK\x15
SYN\x16
ETB\x17
CAN\x18
EM\x19
SUB\x1A
ESC\x1B
IS4\x1C
IS3\x1D
IS2\x1E
IS1\x1F
space\x20
exclamation-mark!
quotation-mark"
number-sign#
dollar-sign$
percent-sign%
ampersand&
apostrophe'
left-parenthesis(
right-parenthesis)
asterisk*
plus-sign+
comma,
hyphen-
period.
slash/
zero0
one1
two2
three3
four4
five5
six6
seven7
eight8
nine9
colon:
semicolon;
less-than-sign<
equals-sign=
greater-than-sign>
question-mark?
commercial-at@
left-square-bracket[
backslash\
right-square-bracket]
circumflex^
underscore_
grave-accent`
left-curly-bracket{
vertical-line|
right-curly-bracket}
tilde~
DEL\x7F
EXAMPLE[[=NUL=]] will match a NUL character.
[\x00] will also match a NUL character.
NOTEPerl regular expressions syntax is used in all products.