What does "host employed" mean?

Someone enters into a contract of employment which states you are being "host employed by X on behalf of Y"?

Alasdair Taylor's answer to What does "host employed" mean? (787824523)

Answer to the question: 

I've never heard this phrase before. It looks like it is used in Australia in some fairly particular circumstances:

"A host employer is an employer who agrees to have an injured worker at their workplace when the worker is unable to participate in rehabilitation with their original employer."