DiscreteDelta[n_1, n_2, ...] gives the discrete delta function \[Delta] (n_1, n_2, ...), equal to 1 if all the n_i are zero, and 0 otherwise.
DownValues[f] gives a list of transformation rules corresponding to all downvalues defined for the symbol f.
Get
(Built-in Mathematica Symbol) << name reads in a file, evaluating each expression in it, and returning the last one.
GraphStyle is an option to Graph and related objects that specifies styles to use for the different graph elements.
IdentityMatrix[n] gives the n*n identity matrix.
Inpaint
(Built-in Mathematica Symbol) Inpaint[image, region] retouches parts of image that correspond to nonzero elements in region.
Inset
(Built-in Mathematica Symbol) Inset[obj] represents an object obj inset in a graphic. Inset[obj, pos] specifies that the inset should be placed at position pos in the graphic. Inset[obj, pos, opos] aligns ...
InterquartileRange[list] gives the difference between the upper and lower quartiles for the elements in list.InterquartileRange[dist] gives the difference between the upper ...
ItemSize is an option for Grid, Column, and related constructs that specifies the sizes to allow for items.
MeanDeviation[list] gives the mean absolute deviation from the mean of the elements in list.