a string giving the name of the table. This is used to name
the layout viewport
grobs
a single grob or a list of grobs
height
a unit vector giving the height of this row
widths
a unit vector giving the width of each column
z
a numeric vector giving the order in which the grobs should be
plotted. Use Inf (the default) to plot above or -Inf
below all existing grobs. By default positions are on the integers,
giving plenty of room to insert new grobs between existing grobs.