Orthogonalize, Normalize and Projection have been added to the built-in Mathematica kernel. Normalize can now take an arbitrary norm function.

InfixNotation[op, func] forces the box structure op to be treated as an infix operator representing the function func in input and output.

file.m is a Mathematica package file.

BoxBaselineShift is an option for AdjustmentBox that specifies how much the baseline of the box should be shifted relative to those of neighboring characters.

CellBracketOptions -> {opt_1 -> val_1, opt_2 -> val_2, ...} is an option for cells that specifies settings for cell brackets.

CheckAbort[expr, failexpr] evaluates expr, returning failexpr if an abort occurs.

ColumnAlignments is an option for the low-level function GridBox that specifies how entries in each column should be aligned.

ColumnLines is an option for the low-level function GridBox which specifies whether lines should be drawn between adjacent columns.

ColumnSpacings is an option for the low-level function GridBox which specifies the spaces in ems that should be inserted between adjacent columns.

CommonDefaultFormatTypes -> {opt_1 -> val_1, opt_2 -> val_2, ...} is an option that specifies default formats for newly created cells.