Use of Greta Macbeth chart

Hi guys,

I have a client who did the first part of a shoot with some bad lighting and poor white balance. He is continuing with another day of shooting and I wanted to recommend a chart he could use that would help me in post. I have used DSC type color charts before and know what I should see in a vectorscope. However I have not used a Greta Macbeth before and since the DSC charts are very expensive the Greta is probably the choice.

In Color, what should I see in the waveform when looking at a Greta Macbeth. Or if the explanation is too lengthy for a forum answer, what resources could I look to for explaining the use of a Greta Macbeth in Color.

Thanks for any info!