I've notised that the issues of Uncanny X-Men from #500-503 as well as #25 of Astonishing X-Men make up an arc called S FX, and all five issues are also included in the Manifest Destiny arc.
Now, I understand that both arcs are stated in the issues (MD on the cover and SFX on the red intro page inside), but what function does having two arcs (particularily since all issues of SFX are a part of Manifest Destiny)?
...also (warning; likely the answer should be obvious), what does 'SFX' even mean? The only time I've ever seen it was (incomprehensibly) short for "sound effects". Is it a common acronym for something else, or something made for this?