When is \if@nobreak set to \iftrue or \iffalse?

In my answer to a question on page breaking, I used a private switch that the user had to set by hand to prevent tables which start just after a section from breaking (at the first line).

It seems that \@nobreaktrue is set after each heading, and restored as soon as the next paragraph begins (see definition of \@afterheading).

Is this the only place where \if@nobreak is altered? Am I right that the intent of this switch is to indicate places where macros should avoid at all costs to insert page breaks?

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\if@nobreak Switch used to avoid page breaks caused by \label after a section heading, etc. It should be GLOBALLY set true after the \nobreak and globally set false by the next invocation of \everypar. Commands that reset \everypar should globally set it false if appropriate.