What does the 'X' in .aspx, docx, xlsx, etc... represent?

Question

Possible Duplicate:
What does X denotes in ASPX, DOCX, XLSX, PPTX etc?

It's one of those things you just take for granted until one day someone asks you and you realize you can't answer it. Much like for years I never questioned the use of 1033 directories in Microsoft products for years until one day, someone asked me about it.

Around the release of .NET and Office 2007, Microsoft added an x to basically all of their extensions and I frankly took it as representing XML, but that simply doesn't make sense with .aspx.

So, I realize this is a very non technical question, but now that the question has been asked of me and my googling hasn't given me an answer, can anyone tell me with authority what the X represents? Is it extended? Xml? Or is there no meaning behind it?

Solution

Here you go.

Comments

[Mukul Kumar Sharma]

Does it need to represent something?

[Admin]

Well, that is very possibly an answer and quite possibly the valid one. So, it could come back the 'X' literally means nothing... that is exactly what I am asking. Generally though, file extensions do represent something.

[jdehaan]

Yes, you've got problems! :-) in the case of aspx it is because it contains xhtml or is an extension of asp. In the case of docx and xlsx it is the Office Open XML format or was it Open Office XML, that was a good MS trick to cause confusion...

[ceejayoz]

"X-tra awesome".

[Serapth]

... sure, make me associate to SuperUser! ;)