Notation help: x before note?

[gt__]

Can someone tell me what an x before a note means?

If you follow this link and look on page 8, the last note in the 12th measure (they're all numbered) has a sort of an x in front of it and I don't know what it represents.

https://www.mutopiaproject.org/ftp/BeethovenLv/O27/moonlight/moonlight-a4.pdf

[bllandes]

It's probably a double sharp

[birba]

"probably"?!

[gt__]

Awesome.. thanks!

I hadn't heard of double sharps before.

So a double sharp is two semi-tones higher than the note written (eg an F turns into a G) 

But if the key signature already says that F is F# like in the example in my first post, then does that double sharped F become a G#? 

[mistermoe]

No, a double sharped F always makes a G, no matter what key signature u have.

[stevebob]

It may be found useful to keep in mind that while F double sharp is played as a G, it doesn't "turn into" G.  Even if it isn't necessary to understand the reason early in one's studies, thinking of F double sharp as G rather than played as G sets the stage for misunderstanding the underlying theory.  (The same applies to any double-sharped or double-flatted notes.)

[birba]

And gt_, how do you denote a double flat? 

[timothy42b]

And gt_, how do you denote a double flat? 

I have played music with Bbb (B double flat) in the key signature.

I wonder if it is theoretically possible to have B triple flat?  I've never seen it and would almost certainly play it wrong the first time anyway!  But I'm curious. 

[gep]

It may be found useful to keep in mind that while F double sharp is played as a G, it doesn't "turn into" G.  Even if it isn't necessary to understand the reason early in one's studies, thinking of F double sharp as G rather than played as G sets the stage for misunderstanding the underlying theory.  (The same applies to any double-sharped or double-flatted notes.)

Indeed. In our present day equal temperament xF= G, but strickly speaking it is slightly different from G (before roughly Bach xF would really be considered different from G!). Hence, it isn't "bogus" to write xF rather than G. For ex., in E major a not on the G line is automatically #G. hence, to get G you can write ♮G or xF; what you would write depends on the harmonic /system logic you are writing in.
But when you see xF, you hit the G key, yes.

I have played music with Bbb (B double flat) in the key signature.

Works the same way, but down then, of course.

I wonder if it is theoretically possible to have B triple flat?

In principle, yes. In reality, no. However there are half#-s and half-b-s. Look in Penderecki. And as for the 31-tone organ (which splits the octave in 31 equal tones), I wouldn't know what sighs they use there. (There is a 31-tone organ in The Netherlands, btw, and music for it. I've just never seen it.

Now lets talk about xB major (with 12 #'s) and have some aspirin...

gep