org-emphasis-regexp-components is a variable defined in `org.el'.
Its value is
(" 	('\"{" "- 	.,:!?;'\")}\\" " 	
,\"'" "." 1)

Components used to build the regular expression for emphasis.
This is a list with five entries. Terminology: In an emphasis string
like " *strong word* ", we call the initial space PREMATCH, the final
space POSTMATCH, the stars MARKERS, "s" and "d" are BORDER characters
and "trong wor" is the body. The different components in this variable
specify what is allowed/forbidden in each part:

pre Chars allowed as prematch. Beginning of line will be allowed too.
post Chars allowed as postmatch. End of line will be allowed too.
border The chars *forbidden* as border characters.
body-regexp A regexp like "." to match a body character. Don't use
non-shy groups here, and don't allow newline here.
newline The maximum number of newlines allowed in an emphasis exp.

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