The TDrawLine structure.

 // DrawLine
 TDrawLine      struct
  Result                sbyte      // The function call result. NO_ERR means it succeeded.
  StartLoc      TLocation  // The location of the starting point.
  EndLoc                TLocation  // The location of the ending point.
  Options       dword          // The options to use when writing to the LCD.
 TDrawLine      ends

See Drawing option constants for valid Options values.