reserved/internally used ids: "home"

dear all

i wanted to create a link object with the id "home" to point to  
"index". silva-2.1 tells me that "home" is reserved for internal use.  
well, i have a link object with id "home" in a silva-1.6.3 site which  
works perfectly without any problems. searching through the svn  
repository it seems that "home" was added to the pool of reserved ids  
in silva-1.4. therefore, my "home" object must have survived all  
upgrades to silva-1.6.3 and it still works. in silva-2.1 i've  
"illegally" renamed the object in the zmi to "home" and i have not  
found any problems so far. so what qualifies "home" to be in the list  
of reserved ids?

regards,
marc