From Second Life Wiki
SetObjectName
llSetObjectName
Description
Function: llSetObjectName( string name );
Sets the prim's name according to the name parameter.
If this function is called from a child prim in a linked set, it will change the name of the child prim and not the root prim.
Caveats
- The name is limited to 63 characters. Longer prim names appeared cut short.
- The LL client did not reliably show the current name. Misleadingly old names sometimes appeared at Edit > General > Name until you closed and reopened the Edit dialog of the prim.