MemoryConstrained[expr, b] evaluates expr, stopping if more than b bytes of memory are requested. MemoryConstrained[expr, b, failexpr] returns failexpr if the memory ...

MouseAnnotation[] gives any mouse annotation associated with the expression at the current mouse position.

Names["string"] gives a list of the names of symbols which match the string. Names[patt] gives a list of names matching the arbitrary string pattern patt.

PermutationLength[perm] returns the number of integers moved by the permutation perm.

lhs === rhs yields True if the expression lhs is identical to rhs, and yields False otherwise.

TableDepth is an option for TableForm and MatrixForm which specifies the maximum number of levels to be printed in tabular or matrix format.

TableHeadings is an option for TableForm and MatrixForm which gives the labels to be printed for entries in each dimension of a table or matrix.

TopologicalSort[g] gives a list of vertices of g in topologically sorted order for a directed acyclic graph g.

Verbatim[expr] represents expr in pattern matching, requiring that expr be matched exactly as it appears, with no substitutions for blanks or other transformations.

$ImportFormats gives a list of import formats currently supported in your Mathematica system.