That's a bad example of how to express age limits. If I've just had my 60th birthday, or perhaps today is my birthday, which applies, or do I have to fill in both forms?

Also, is it my age at the time I sign the form, or my age at the time the form is received, that matters? Arguably that's a problem with the rule itself rather than how it's expressed. It's better if you can write something like: "If you were born before 6 April 1960 ... otherwise ...". Note that "after 6 Apr 1960" is arguably more ambiguous than "before 6 Apr 1960" because there's a slight risk that someone could interpret "6 Apr 1960" as meaning 1960-04-06 00:00:00.

This problem is vaguely related to the insurance policy renewals that leave a one-minute gap between the old policy and the new policy, and even more vaguely related to the ambiguity of "midnight on the next day".

> It's better if you can write something like: "If you were born before 6 April 1960 ... otherwise ...". Note that "after 6 Apr 1960" is arguably more ambiguous than "before 6 Apr 1960" because there's a slight risk that someone could interpret "6 Apr 1960" as meaning 1960-04-06 00:00:00.

I strongly prefer pairing “before” and “on or after” (or “on or before” with “after”) when it comes to dates. “On <date>” is widely and conventionally understood to encompass the entire day, and it seems to make it far less likely than with after/before alone with “otherwise” that people will trip up over boundary conditions. But the right phrasing is highly sensitive to the context and the underlying rule; if it's an age based rule and you have fixed text that doesn't dynamically adjust by dates you can't use date-based language even if it would be clearer.

Oh man I'm having day nightmare flashbacks about the time I spent days parsing some well-meant European Energy-Saving directive and figuring out whether we could sell a PC with a fixed-frequency CPU, and all power- and energy-saving features disabled (latency concerns). Ouch... There were some official and unofficial logic diagrams and they made things even worse. Lexicon was pretty vague, use-cases too, exceptions too... and you end up writing some kind of justification for you being one of the special cases and praying it's OK. And it wasn't even the worst normative document I've ever read. It was clear about the spirit of the directive...

Imprecise language to allow flexibility and 'let the judges decide'... I'm not sure I'm comfortable with common-law-inspired regulation.

Not sure how to do this better though.

I disagree. Putting the "if" clause first means you can skip this sentence. In other words, the if-sentences are guard clauses to the default option (fill form 331).

In other words, it's not really an if-else block, but just an if statement before the default scenario. Almost everyone has to fill form 331.

I think the sentence structure you suggest would quickly make a longer text tedious to read. I have experimented with that sentence format, and it added a lot of text, but not a lot of clarity.

I also think that putting the if statement at the end makes little sense, just like when reading code.