Hi Karen, I wanted to answer to you in this post so that it would be useful to others too. Two of the notations in the chart are from Schminke’s watercolors brochure.
The empty square stands for completely transparent,
square with a diagonal – semi transparent
half filled square – semi opaque
completely filled square – opaque
The empty triangle is for non staining
half filled triangle is for semi staining
completely filled triangle is for staining
The empty circle is for non sedimentary
circle with dots is for sedimentary
I’m quite happy with my schminke colors but I wanted more hues so I opted for other brands. My first criteria was lightfastness, the next important property was transparency.