Hebrew jussive vs. imperfect

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For Psalm 40:3 (=MT 40:4) the BHS has the verb יִרְאוּ
tagged as an imperative ("many will see"). The NET notes however see this as jussive ("may many see"). Are the forms of the jussive and imperative identical here in the Hebrew? What has be confused is that in my paradigm charts in the BHRG

1) the Jussive is always listed as 3rd pers sing. but the above word is tagged as 3rd pers plural.

2) the jussive is supposedly a shortened form of the imperative (although that seems to contradict the paradigm charts where it the same...)

Ben

The difference between the jussive and imperfect is only visible in a few cases, such as III-weak verbs (but not every form), hollow verbs, and hiphils (with strong verbs too). The form of the verb used for the jussive (if it differs from the normal imperfect) is also the form used in the so-called vav-consecutive (except with hollow verbs, for linguistic reasons that I can lay out if you want...)

At an earlier (reconstructed) stage of Hebrew, imperfect verbs had a final vowel on them indicating mood. A normal imperfect would be yaqtulu, a jussive yaqtul, with no final vowel. That's why it's called the shortened form. (This is based on observed changes in Hebrew, as well as comparative semitic data with Arabic and other languages which have preserved the final mood vowel.)

Formally speaking, there's no way to tell if this form is jussive or imperfect (though context might help.) The forms are  identical in the 3pl of III-weak verbs.