Assertion

 const bit [7:0] SKP = 'h1C;
  const bit [7:0] FTS = 'h3C;
  const bit [7:0] SDP = 'h5C;
  const bit [7:0] IDL = 'h7C;
  const bit [7:0] COM = 'hBC;
  const bit [7:0] EIE = 'hFC;
  const bit [7:0] PAD = 'hF7;
  const bit [7:0] STP = 'hFB;
  const bit [7:0] END = 'hFD;
  const bit [7:0] EDB = 'hFE;   

property control_rxdata_p(x,width_check);
     `ASSERT_RXEVENT
     ( RxDataK[x]      && 
       PowerDown == P0 && 
       RxValid         && 
       width_check     &&
       !RxElecIdle     &&
       Rate inside {0,1} &&
       RxStatus == 3'b00 ) |-> ( RxData[x*8 +:8] == SKP ||
                                 RxData[x*8 +:8] == FTS ||
                                 RxData[x*8 +:8] == SDP ||
                                 RxData[x*8 +:8] == IDL ||
                                 RxData[x*8 +:8] == COM ||
                                 RxData[x*8 +:8] == EIE ||
                                 RxData[x*8 +:8] == PAD ||
                                 RxData[x*8 +:8] == STP ||
                                 RxData[x*8 +:8] == END ||
                                 RxData[x*8 +:8] == EDB );

      assert property (control_rxdata_p(0,1))
   begin
     `EVALUATED("EI_PCIE_PL_ERR_148")
   end
   else
   begin
     `FIRED("EI_PCIE_PL_ERR_148",$sformatf("Control characters are not present at RxData[7:0] = 8'h%0h",RxData[7:0]),_agent._cfg.is_active, "RX")
   end

   EI_PCIE_PL_ERR_003_RX_15_8:
   assert property (control_rxdata_p(1,Width inside {1,2}))
   begin
     `EVALUATED("EI_PCIE_PL_ERR_149")
   end
   else
   begin
     `FIRED("EI_PCIE_PL_ERR_149", $sformatf("Control characters are not present at RxData[15:8] = 8'h%0h",RxData[15:8]), _agent._cfg.is_active, "RX")
   end

-Question) I am not getting : 1) RxStatus == 3’b00 ) |-> ( RxData[x*8 +:8] == SKP || , are they converting string into a fixed size integral?
2) assert property (control_rxdata_p(0,1)), what is this 0,1?
3) assert property (control_rxdata_p(1,Width inside {1,2})), what is this width inside {1,2} ?
please help