TabSpacings
is an option for character selections that specifies the number of spaces in ems that the cursor advances when the 
key is pressed.
TabSpacings
This function has not been fully integrated into the long-term Wolfram Language, and is subject to change.
is an option for character selections that specifies the number of spaces in ems that the cursor advances when the 
key is pressed.
Wolfram Research (1999), TabSpacings, Wolfram Language function, https://reference.wolfram.com/language/ref/TabSpacings.html.
Text
Wolfram Research (1999), TabSpacings, Wolfram Language function, https://reference.wolfram.com/language/ref/TabSpacings.html.
CMS
Wolfram Language. 1999. "TabSpacings." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/TabSpacings.html.
APA
Wolfram Language. (1999). TabSpacings. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/TabSpacings.html