split-string-default-separators

split-string-default-separators is a variable defined in `subr.el'.
Its value is

"[ 	

]+"

• This variable may be risky if used as a file-local variable.

Documentation:
The default value of separators for `split-string'.

A regexp matching strings of whitespace. May be locale-dependent
(as yet unimplemented). Should not match non-breaking spaces.

Warning: binding this to a different value and using it as default is
likely to have undesired semantics.