The listing is of decrees made by the High Court of Chancery in London as reported on the official “London Gazette”, available online at 'http://www.london-gazette.co.uk/ .

They occur when in litigation it was necessary to, mainly, call for creditors or legatees to make claims. The Gazette’s wording is usually “pursuant to a decree”, occasionally “whereas by a decree”, of the High Court of Chancery. The parties named in the “cause” or case are often given to help finding them in the National Archives’ “equity suits”, as explained in their leaflet “Chancery Equity suits after 1558” http://www.nationalarchives.gov.uk/records/research-guides/chancery-equity-from-1558.htm, which is essential reading when researching such litigation.

When trying to find them in the National Archives catalogue http://www.nationalarchives.gov.uk/catalogue/search.asp (which will not always be successful) limit the search to the C class.