The EnableParseRule command turns on the specified parse rule(s) in the Typesetting package for use in 2-D input, while the DisableParseRule command turns off the specified parse rule(s) in the Typesetting package for use in 2-D input. The QueryParseRule command shows whether a rule is enabled or not. It returns a set of elements a=b where a is a rule name and b is true if a is enabled and false otherwise.

There are too many rules to be able to list them all here, but all are available in the Rules area of the interactive Typesetting Assistant.

As a simple example, the rule $''BesselJ''$ corresponds to the capability of parsing the function $J$ with a symbolic subscript (say $v$) as a function a single variable (say $x$) as the BesselJ function ($\mathrm{BesselJ}\left(v\,x\right)$).

The Typesetting[QueryParseRule] command was introduced in Maple 2017.

For more information on Maple 2017 changes, see Updates in Maple 2017.