How to create a knitting chart using MacBook's Numbers

I like or would say prefer working with schematics in my knitting projects. Mostly I use well known and documented patterns and some times I need to design my own which specifically has to feet to the garment. In this case I use Numbers (a part of iWork package on MacBook). Newly designed charts are easy-to-read and easy-to-store. I guess it could be done in Excel as well.
First I select plane table and re-size all columns, second I use symbols and background colors for the stitches identification and third and last I add a description and save it.

Here is a screen shot of the Numbers with a chart what was translated into a border for a baby blanket