In English (and this entire discussion applies pretty much to Dutch as well), there are many alternatives for expressing that a rule applies to all cases. Among these alternatives, it is convenient to choose a simple indefinite article (a or an - click here for the difference).
“A client ...” means: “Each time a client comes along who spends …”:
A client who spends over € 50,000 in a given year
must be assigned a Personal Coach.
|Every client who spends ...
|All clients who spend ...
|Clients who spend ...
|Each client who spends ...
|Any client who spends ...
The alternatives really mean exactly the same thing. But if you stick with a(n)…,
- Your readers do not need to switch between all these alternatives and worry if perhaps the differences mean something.
- A rulebase with many rules is easier to scan through if you go for uniformity.
- As a writer, you do not need to make a choice between alternatives that mean the same thing anyway.
If you have 2 times a, usually one of these must be replaced by the:
|The destination port of a flight booking must be specified.
|A destination port of a flight booking must be specified.
If there are no conditions at all, a sounds strange. Prefer each in these cases:
|Each Gold Card customer must be assigned a personal coach.
|A Gold Card customer must be assigned a personal coach.
With a(n) …, you write in the singular. As a result, you are often confronted with he or she:
|An incoming passenger must pass ID control before she is allowed to pass customs.
|Incoming passengers must pass ID control before they are allowed to pass customs.
One simple gender-neutral strategy is to switch regularly between he and she, just randomly choosing one or the other. You can also write he or she but this makes a rule harder to read.
… is the fact that … is a set phrase that always contains the, not a:
|A flight booking is the fact that a client books a flight.
|A flight booking is a fact that a client books a flight.