It is possible to define faster several identical object types with different names using the keyword alias. If the section !def of the initialization file contains for example the following :
!def ; Objects of type 1 (comment line) defobj1 -1 0 2 Objects of type 1 : ndim1_1 ndim1_2 nb1 ; Objects of type 1b (comment line) defobj1_b alias defobj1 Objects of type 1b :
the object type defobj1 will first be created. Then another object type called defobj1_b will be created, which will be identical to defobj1 (i.e. they have the same parameters, except the comment defining it). In this case the definition of defobj1_b needs only three lines : in the first is the name of the command defining the objects of this type, in the second we put the keyword alias followed by the name of a previously defined object type and in the third the comment defining the object type.
It is possible to see in a program if an object type is an alias of another. For this we use the global variable
int *Obj_alias;
If the object type number i is not the alias of another object type, the integer Obj_alias[i] will be equal to i. If this object type is the alias of the object type j then Obj_alias[i] will be equal to j (in this case j is smaller than i). This array can be used for instance if one wants to write commands using object types which are the aliases of one object type.