What is the meaning of 'se' in this sentence

[Tdeluco]

I understand that there are several variations/uses of the pronoun 'se' (including as an indirect object pronoun, with a reflexive verb, with passive voice, and the impersonal 'se'), but sometimes I see it written and it doesn't seem to fit any of these categories. It also seems superfluous.

For example: ¿Cuando se escribió este libro?

It may be obvious, but I don't understand what form of 'se' is used in this sentence.

Any help?

[Rusty]

This could be either the impersonal 'se' usage or an example of the 'pasiva refleja' construct.

The closest translation to the impersonal usage is "When did they write this book?" (where 'they' doesn't refer to anyone in particular)

The closest translation to the 'pasiva refleja' construct is the English passive voice - "When was this book written?"

Welcome to the forums!

UPDATE: I thought about both the impersonal and the 'pasiva refleja', so included both. Then I noticed AdA's post which concurs with the addition I made. I still think both constructs fit. ¿Me equivoco?

[AngelicaDeAlquezar]

I agree with Rusty about the translation, but for me this sentence is using the "voz pasiva refleja".

- El libro fue escrito. (Voz pasiva.) -> Se escribió el libro. (Voz pasiva refleja.)

[Tdeluco]

The 'pasiva refleja' translation does make sense. I think I need to try to gain a better understanding of this usage. The impersonal usage could also work. The context (which I did not provide for some reason) suggests that it is 'pasiva refleja' usage is correct. Thanks for the help.

[AngelicaDeAlquezar]

@Rusty: I think you're right, both constructions might overlap.