You need to identify that line in the whole body of the text first. You have to remember computers are very dumb and very literal. What seems obvious to you as a person is not the way a computer looks at it.
This can be handled in different ways and would still require testing with your actual data.
This is a simple teaching edition example based on your particular parameters…
tell application id "DNtp"
repeat with thisRecord in (selection as list)
set recordText to (plain text of thisRecord)
-- Get the plain text of the file
repeat with currentLine in (paragraphs of recordText)
-- Loop through the paragraphs in the text
set lineWords to (words of currentLine)
-- Get the words in the current line
-- This returns a list of words
if (count characters of (item 1 of lineWords as string)) = 10 then
-- Check if the first item in the list has 10 characters in it (per your example)
set possibleMatch to (item 1 of lineWords)
-- If it has 0 characters, set it as a possible match for further validation
try -- This is used to do a process without an error necessarily stopping the script
(possibleMatch as real)
-- Validating if the first word is a number or not. If it's a word, it obviously can't be coerced into a numerical value.
-- i.e., you can't say "What is apple minus three?"
display alert "" & (item 4 of lineWords)
-- If it is a number, we are displaying the fourth word (again, per your example).
-- If the number is matched, here is where you'd do stuff with the "pssibleMatch" variable.
exit repeat -- Stop looping since there's no reason to continue after the match has been made.
end try -- Otherwise, end trying when it errors and continue on looping to the next line…