if (colTo < colFrom) {
throw new IllegalArgumentException("The 'to' col (" + colTo
+ ") must not be less than the 'from' col (" + colFrom + ")");
}
MergedCellsTable mrt = getMergedRecords();
mrt.addArea(rowFrom, colFrom, rowTo, colTo);
return mrt.getNumberOfMergedRegions()-1;
}