'TextAreaChar' and 'TextAreaLine'

I can't understand how to use 'TextAreaChar' and 'TextAreaLine'. I can't understand documentation. It's to simple for this moment. Any one could supply an examples.. Thanks

TextAreaChar :
L1- xxxxxxxx
L2- xxxxIxxx
L3- xxxxxxxx

I is 17th char in text
"textareachar txtgadget,17" will return 2

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TextAreaLine :
L1- xxxxxxxx
L2- Ixxx
L3- xxxxxxxx

I is 17th char in text, it is the first char in L2 line
"textarealine txtgadget,2" will return 17