An attempt has been made to insert a set member into a primitive set using the @INSERT function.  Set members may only be inserted into derived sets, and the member being inserted must be a member of the derived set's parent primitive sets.  The following example illustrates:

MODEL:

 

SETS:

S1 /M1, M2, M3/;

S2( S1);

ENDSETS

 

CALC:

 !The following is valid because M2 is a member

  of S2's parent primitive set, S1;

 @INSERT( S2, @INDEX( M2));

 

 !The following is not valid because M4 is not a

  member of S1;

 @INSERT( S2, @INDEX( M4));

 

 !The following is not valid because S1 is not a

  derived set;

 @INSERT( S1, @INDEX( M4));

ENDCALC

 

END