'for' attribute is not defined in JSF

Great finding from my colleague. When retrieve systemout.log from WebSphere Application Server, noticed that the following warning seem to be flooding in the log.

Attribute 'for' of label component with id xxxxxxxxxxxxxxxxxxxxxx is not defined 

This warning is due to the missing of attribute 'for' in a component being called. For example,

The purpose is to let the outputlable know which component to label. For suppressing the excessive non-informational logging line, always practise to use the 'for' attribute.