In Wolfram Language / Mathematica, there are the following
escaped characters that end with `Space`

:

```
$WhiteSpaceCharacters = {
"\[AutoSpace]",
"\[COMPATIBILITYKanjiSpace]",
"\[InvisibleSpace]",
"\[LetterSpace]",
"\[MediumSpace]",
"\[NegativeMediumSpace]",
"\[NegativeThickSpace]",
"\[NegativeThinSpace]",
"\[NegativeVeryThinSpace]",
"\[NonBreakingSpace]",
"\[RawSpace]",
"\[ThickSpace]",
"\[ThinSpace]",
"\[VeryThinSpace]"
}
```

These can be found by evaluating `?\[*Space]`

in a
Mathematica notebook.

To actually obtain these in copiable text was not
straightforward for me as I did not find a programmable way to
generate the above list. Instead, I copied the cell expression out
(by selecting the output cell, pressing
`Ctrl`+`Shift`+`E`, and copying out the
text), and then run `ack`

to extract any strings that
start is sandwiched with `\[`

and `]`

:

```
17:09:43 meng@meng2maclap:~/Temp$ ack -o "\\\\\\\\\[.*Space\]" cellexpr.txt | sort | uniq
AutoSpace
COMPATIBILITYKanjiSpace
InvisibleSpace
LetterSpace
MediumSpace
NegativeMediumSpace
NegativeThickSpace
NegativeThinSpace
NegativeVeryThinSpace
NonBreakingSpace
RawSpace
ThickSpace
ThinSpace
VeryThinSpace
```

Curiously, only `\[AutoSpace]`

,
`\[NonBreakingSpace]`

, `\[RawSpace]`

satisfy
```
StringMatchQ[#,
RegularExpression["[[:whitespace:]]"]]&
```

.

See the CDF file for details.