[newvc].
'Command examples:       CHECK|: newvc.'.
'                        CHECK|: newvc 2.'.
''.
'This command invokes the checker on a particular VC; you are asked for'.
'the number of the VC you wish to work on and this VC is then copied into'.
'the checker\'s current workspace ready for your proof-attempt.  The VC'.
'must be one of those loaded in from a .VCG file.'.
''.
'If all VCs have been proved, the command will fail.  If the VC number'.
'which you have supplied is non-existent (either because it is too large'.
'or because you have already proved that particular VC), you will be'.
'told which VCs remain to be proved and prompted to try again.'.
''.
'A new feature, introduced in version 1.2, is that if you type "newvc"'.
'before you have completed your proof of the currently-selected VC, you'.
'will be prompted to confirm that you wish to abandon the current proof'.
'attempt.  Type "yes" to abandon the proof and execute the "newvc"'.
'command, or "no" to abandon the "newvc" and return to the current proof.'.
