如有疑問

例: This is what you INTEND to do should you encounter sexual temptation on the Web.

Should you... 即 If you...，是一種倒裝句。

網友的useful comment: 
from: http://forum.wordreference.com/showthread.php?t=292455

1. It's just another way of expressing the second (or third) conditional by the means of auxiliary-subject inversion.

More examples
If I were to find a treasure I'd buy a castle.
--> Were I to find a treasure, .....

If he hadn't been there, we would have lost the game
---> Had he not been there, we.....

In both sentences we have inverted the subject and the auxiliary (or modal). Plus we no longer need the if.

It's both more idiomatic (in the sense that this wording is specific to English) and slightly more formal.

2."Should" is often used in a business context like this because to some people, it sounds more formal. In short, it replaces "if."

There is also a subtle idea about "should" in that it is supposed to express a minimal amount of doubt.

If you have any questions (I don't know if you will or not), please don't hesitate to ask. 

Should you have any questions (and I rather doubt you will), please don't hesitate to ask.

3. Should you have" is the future/conditional of "Do you have."

It's used as such so the statement represents a more vague representation of time. It doesn't demonstrate just "now" and the "present" but also the "future."

Another way to make the same statement is "If you have" but this only represents future, and not conditional. And "If you will have" represents both, but is not in use because "should" is much easier to state than "if - will."