Sentence:  A modification, using larger intergrade differentials between the lower grades and with differentials gradually decreasing in size as the <WSD>payline</WSD> moved upward through higher grades, solved both problems- - providing more nearly competitive rates at GS-5 and 08-7 and a OS-18 rate which was much lower and more reasonable in the Federal context 
Meaning of the word marked with <WSD> tags:  The minimum salary associated with a pay grade.