patt /; test is a pattern which matches only if the evaluation of test yields True. lhs :> rhs /; test represents a rule which applies only if the evaluation of test yields ...
DateTicksFormat is an option for DateListPlot which specifies how date tick labels should be formatted.
x-- decreases the value of x by 1, returning the old value of x.
DigitBlock is an option for NumberForm and related functions that specifies the maximum length of blocks of digits between breaks.
EdgeLabelStyle is an option and property for Graph and related functions that specifies the style to use for edge labels.
Except
(Built-in Mathematica Symbol) Except[c] is a pattern object which represents any expression except one that matches c. Except[c, p] represents any expression that matches p but not c.
FractionBoxOptions -> {opt_1 -> val_1, opt_2 -> val_2, ...} is an option for cells that specifies settings for FractionBox objects within the cell.
FrontEndEventActions is an option for the notebook front end that gives a list of actions to perform when specified user-interface events occur.
FrontEndToken["cmd"] is an object which represents a front end command token, typically corresponding to a front end menu item, to be executed by FrontEndExecute. ...
FunctionExpand[expr] tries to expand out special and certain other functions in expr, when possible reducing compound arguments to simpler ones. FunctionExpand[expr, assum] ...