Sorry, I glanced through your link but didn't spot the "ex" reference before answering. Now that I've seen it, I agree with Conor that it's Eurospeak and probably not something you'd see in a US or UK legal text.
If you want to use Eurospeak, still, make sure it's the same thing: were articles 1156 to 1164 renumbered, but not otherwise changed? If so, then the word you want is definitely "formerly." That means it's the same statute but it simply got renumbered.
To understand what your EU reference means, look at this PDF:
https://assets.publishing.service.gov.uk/government/uploads/... Your EU cite is to the Treaty on the Functioning of the European Union (TFEU), and it says, "Article 115 (ex Article 94 TEC)" (TEC = Treaty Establishing the European Community). The link above is a table comparing the provisions of the TFEU to those of the TEC. On p.17 it says Art. 115 of the TFEU is "in substance the same" as Art. 94 of the TEC. On p.6, it explains what that means: "where the wording has changed, or existing provisions have been combined, but the substance has not changed."
Which is not the same thing as just renumbering.
peer agreement (net): +1