An administrator is defining an lpp_source called lpp_AIX6 in NIM when the following warning message is displayed in the output：  
warning： 0042-267 c_mk_lpp_source： The defined lpp_source does not have the ’simages’ attribute because one or more of the following packages are missing：
bos  
bos.net  
bos.diag  
bos.sysmgt  
bos.terminfo  
bos.terminfo.all.data  
bos.mp64  
devices.common  
bos.64bit 
What does this warning message mean？（）