There's a useful explanation here: http://www.usinenouvelle.com/article/roquefort-condamne-pour...

Under this kind of agreement, a company is obliged to list a supplier's full product range in order to get maximum discounts. In the case described in the article above, the supplier had a dominant position in the market and a large product range, so listing the entire range effectively froze out other suppliers.

Example:

This is another question we get asked a lot! We see comments on our social posts from people who don’t seem to understand what it means to be ‘tied’ and also don't understand that this is not a negative thing - it actually has many positive attributes for the business owner.

So, as an outline, many pub tenancy agreements are a ‘full tie’ which means that the pub company will ask you to purchase all products including beers, cider, wines, spirits and all other drinks from them.

The purpose of a tied agreement is normally so that the pub company can offer competitive rent and other support services, which they can then recoup part of the cost through the sale of beers and other drinks.

Some pub companies do offer a ‘partial tie’ agreement which gives you more freedom to purchase products from other breweries and suppliers too.

https://www.everards.co.uk/run-a-pub-with-us/blog/whats-tied...

Tie-In Arrangements
Marketing dictionary
Tie-In Arrangements

an arrangement in which a manufacturer sells a product to a reseller only on condition that the reseller also buys another less popular product; also called a Tying Contract. Tie-In Arrangements are usually illegal under the Trade Practices Act.

https://www.monash.edu/business/marketing/marketing-dictiona...