effective immediately

Yes, that's fine. It's common usage, in fact.

The Secretary for Development has resigned, effective immediately.

It sounds OK to me, but I'm not sure, because the adjective effective in this case is modifying the sentence in front, while I know adverbs very often do the job, but not adjectives.

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I'm not so sure that 'effective' alone is modifying the first part.

The Secretary for Development has resigned, which is effective immediately.

But, JTT, do you not think when WHICH functions as a non-restrictive relative pronoun WHICH IS/ARE etc. are very often omittable?

The Secretary for Development has resigned, effective immediately.

It sounds OK to me, but I'm not sure, because the adjective effective in this case is modifying the sentence in front, while I know adverbs very often do the job, but not adjectives.

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jtt:


The reason I said that, above, is that it seems to me the word 'effective' can't
stand alone as a modifier,

??The Secretary for Development has resigned, effective.??

??Effective, the Secretary for Development has resigned.??



The Secretary for Development has resigned, which is effective immediately.

Again, I'm not sure at this point, WB. Though they can be omitted in certain instances, they are understood.

I'm thinking that this is a full/complete sentence defining relative clause, as in,

He has the afternoon off, which is nice.

[example from CGEL, ... , I think]

I say this because the understood relative pronoun, which, can't be 'resigned' or 'has resigned'.

??The Secretary for Development has resigned. The has resigned/resigned is effective immediately.??

The Secretary for Development has resigned. The resignation is effective immediately.