SvPVIV – string & integer 

$s++;
SV = PVIV(0x1f7fdb8) at 0x1f8baa8
  REFCNT = 1
  FLAGS = (IOK,pIOK)
  IV = 43
  PV = 0x1f84cf0 "42"\0
  CUR = 2
  LEN = 16