\multicolumn{cols}{pos}{text}
The \multicolumn is used to make an entry that spans several
columns. The first mandatory argument, cols, specifies the
number of columns to span. The second mandatory argument, pos,
specifies the formatting of the entry; c for centred, l
for flushleft, r for flushright. The third mandatory argument,
text, specifies what text is to make up the entry.