Hi Mesfer
Basically these are for implementing Dynamic Half Rate,
FRL – the % when the available TCH is used up, suppose if its 60% and the cell has 2 TRX ie around 13 usable FR TS so when 60% of 13 = around 7 or 8 TCH are in use then BSC will dynamically start converting the FR TS to HR RS. since i am not familiar with your specific vendor there will be another parameter which will specify the holding time of converted HR TS and another parameter to convert them back to FR when congestion gets over