"To do something, it's required to do something else" - Is this construction correct?

Question

I have a technical document with the following sentence:

1. Exception: To assign a_very_special_variable, use a separate line.
2. Exception: To assign a_very_special_variable, it’s required to use a separate line.

I want to avoid the word "exception" and—for this reason—it seems I need to use the second version of the sentences and not the first.

However, I'm not really sure that the second version is really grammatically correct. I tried to find such sentences over the Internet and I have found nothing.

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The following part was added after the conversation with BadZen in comments

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The document is a style guide for AutoHotkey programming language. There is a following section:

Comma-separated expressions

Use them only if it really makes sense to do so.

FirstName := "John", LastName := "Doe"
Age := 20

Warning

To assign CliboardAll, use a separate line.

; OK
Clipboard := "Foo"
PseudoClipboard := ClipboardAll
Clipboard := PseudoClipboard
MsgBox,,, % Clipboard  ; => `Foo`

; Wrong
Clipboard := "Foo", PseudoClipboard := ClipboardAll, Clipboard := PseudoClipboard
MsgBox,,, % Clipboard  ; => An empty string

The first rule is just a matter of taste.

The second (that is, the one inside "Warning") is mandatory; if you break it, you get an error.

Answer 1

To assign a_very_special_variable, use a separate line.

is perfectly fine and preferably brief.

The second sentence is clear, but could be better worded:

To assign a_very_special_variable, the use of a separate line is required.

You could probably use either with "Exception:" in front, or without it - even though this is not strictly and properly grammatical, it is common-use and also clear what you mean.