PROTONSHIFTS {proton-shift-statement>} END 
  OBSErved <sel> [<sel>] <real> [<real>] ! set the 
       ! observed proton shift or shifts for the protons 
       ! in the selection(s) to the real value(s).
  RCOIl <sel> <real> ! set the random coil proton shift
       ! for all the protons in the selection
       ! to the real value(s).
  ANISotropy <sel> <sel> <sel> <CO|CN> <isCOOH> <SC | BB>
       select Ca     CO    O  atoms (one in each selection)
       say if its a CO or CN bond, if its part of
       a carboxyl group (which are averaged together),
       and whether it is a backbone or sidechain CO.
  AMIDes <sel> ! select all the backbone amide protons.
  CARBons <sel> ! select all the BB carbonyl carbon atoms.
  NITRogens <sel> ! select all the BB nitrogen atoms.
  OXYGens <sel> ! select all the BB oxygen atoms.
     <sel> <sel> <sel> <sel> <sel> [<sel>]
     say how many atoms are in the ring, and select 
     each one in turn. The last selection is only for 
     six-member rings.
  ALPHasandamides <sel> ! select both alpha and amide 
  CLASsification <name> ! Starts a new class. Applies to all 
       ! ASSIgn and FORCe entries until another CLASS entry 
       ! is issued. 
  ERROr <real> ! the error to be used by the current 
       ! class in square well calculations (default = 0.3)
  DEGEneracy <1 | 2> ! Set the number of shifts 
       ! to be averaged for each observation 
       ! in this class {default = 1} 
  FORCeconstant <real> [<real>] ! force constant and 
       ! Constantine force constant for all 
       ! assignments in the current class. (defaults = 0.1) 
  POTEntial <SQUAre | HARMonic> ! use shift errors or not
  PRINt THREshold <real> <ALL | CLASs <name>> <RMSD|NORMsd>!
       ! prints proton  
       ! shift violations greater than the specified value (in 
       ! ppm) for all classes or for the specified class 
       ! and potentially prints the results to the RMSD array
  RESEt  ! erases the proton shift assignment table

Xplor-NIH 2023-11-10