"(?s)(?<=Hello).*(?=Regards)"
or
"(?s)(?<=Hello).*?(?=Regards)"
or
str pattern = "(?s)Hello(.*)Regards"
i=findrx(txtIndex pattern 0 0 letterContent 1)
or
"(?s)(?<=Hello).*?(?=Regards)"
or
str pattern = "(?s)Hello(.*)Regards"
i=findrx(txtIndex pattern 0 0 letterContent 1)