Using regex in relevant field?

[MatthewHenderson1]

In the form, I am asking the person to record the hue, value and chroma of the soil they are looking at. Based on their input, I have a text read only field that will display the soil color name. For example if the hue is Gley 1 the color will be white so in the relevant field I have ${hue}='gley1' . I need to do something more complex that requires regex but not sure of the syntax. Would it be ${hue}=regex([A-Z]\w) or regex(${hue},"[A-Z]\w")? 

[MatthewHenderson1]

Got it. I'm using the Munsell soil color chart and the result for when someone selects Hue: Gley 1 Value: 8 Chroma: N will popup as white when the following code is entered into the 'relevant' field:

regex(${hue},'g.*') and regex(${value},'8') and regex(${gley1},'n')