how come they only provide family visit visa for my wife for only 1-month and and extended additional 5-months if there were a VISA FOR WIFE for 1-year or more?

Please see this link: http://english.mofa.gov.qa/visa.htm

read item number 2 for VISIT VISA FOR WIVES AND CHILDREN.

now my wife will finish her 6-months visit visa. Can I extend her for additional few months? or can I use this visit visa for wife??? Please enlighten me with this case. Thanks!