How does Windows recognize the file as Excel's?
 

I'm using Excel2002 on Windows2000.
I had a book whose name is a.xls.
And I changed its name to a.ddd in order not to start Excel.exe by double
clicking the file.
But double-clicking the file, Excel.exe starts.
How does Windows recognize the file as Excel's data file?

How does Windows recognize the file as Excel's?
 

it first looks in the registry to see if it has a defined application
for that extension. if not it looks at the first 8 bytes in the file
and recognizes it as biff8. (excel97-2003)


--
keepITcool
| www.XLsupport.com | keepITcool chello nl | amsterdam


Zoo wrote in

I'm using Excel2002 on Windows2000.
I had a book whose name is a.xls.
And I changed its name to a.ddd in order not to start Excel.exe by
double clicking the file.
But double-clicking the file, Excel.exe starts.
How does Windows recognize the file as Excel's data file?

How does Windows recognize the file as Excel's?
 

Thank you , keepITcool.
I changed the first 2 byte of a.ddd from D0 CF to 0D FC with a binary editor
as a test.
Then Excel.exe no more starts.

Can I as one more question?
Could you tell me the URL in which the meaning of the first 8 bytes of biff8
is decribed?

"keepITcool" wrote in message
.com...

it first looks in the registry to see if it has a defined application
for that extension. if not it looks at the first 8 bytes in the file
and recognizes it as biff8. (excel97-2003)


--
keepITcool
| www.XLsupport.com | keepITcool chello nl | amsterdam


Zoo wrote in

I'm using Excel2002 on Windows2000.
I had a book whose name is a.xls.
And I changed its name to a.ddd in order not to start Excel.exe by
double clicking the file.
But double-clicking the file, Excel.exe starts.
How does Windows recognize the file as Excel's data file?

How does Windows recognize the file as Excel's?
 

it's an identifier used for OLE and ATL.
i havent got any indepth knowledge of this.

personally i wouldn't fiddle with the bits
other than for testing and curiosity.



--
keepITcool
| www.XLsupport.com | keepITcool chello nl | amsterdam


Zoo wrote in

Thank you , keepITcool.
I changed the first 2 byte of a.ddd from D0 CF to 0D FC with a binary
editor as a test.
Then Excel.exe no more starts.

Can I as one more question?
Could you tell me the URL in which the meaning of the first 8 bytes
of biff8 is decribed?

"keepITcool" wrote in message
.com...

it first looks in the registry to see if it has a defined
application for that extension. if not it looks at the first 8
bytes in the file and recognizes it as biff8. (excel97-2003)


--
keepITcool
www.XLsupport.com | keepITcool chello nl | amsterdam


Zoo wrote in

I'm using Excel2002 on Windows2000.
I had a book whose name is a.xls.
And I changed its name to a.ddd in order not to start Excel.exe by
double clicking the file.
But double-clicking the file, Excel.exe starts.
How does Windows recognize the file as Excel's data file?

How does Windows recognize the file as Excel's?
 

Thank you for quick replying .
It seems difficult to understand the exact meaning.
Any way , thanks to you, I succeeded in preventing from Excel starting.

"keepITcool" wrote in message
.com...

it's an identifier used for OLE and ATL.
i havent got any indepth knowledge of this.

personally i wouldn't fiddle with the bits
other than for testing and curiosity.



--
keepITcool
| www.XLsupport.com | keepITcool chello nl | amsterdam


Zoo wrote in

Thank you , keepITcool.
I changed the first 2 byte of a.ddd from D0 CF to 0D FC with a binary
editor as a test.
Then Excel.exe no more starts.

Can I as one more question?
Could you tell me the URL in which the meaning of the first 8 bytes
of biff8 is decribed?

"keepITcool" wrote in message
.com...

it first looks in the registry to see if it has a defined
application for that extension. if not it looks at the first 8
bytes in the file and recognizes it as biff8. (excel97-2003)


--
keepITcool
www.XLsupport.com | keepITcool chello nl | amsterdam


Zoo wrote in

I'm using Excel2002 on Windows2000.
I had a book whose name is a.xls.
And I changed its name to a.ddd in order not to start Excel.exe by
double clicking the file.
But double-clicking the file, Excel.exe starts.
How does Windows recognize the file as Excel's data file?

How does Windows recognize the file as Excel's?
 

But your problem is that the file probobly now won't work at all. Maybe you
should change it to .txt or something instead of fiddling with the binary
data.

Jeff

"Zoo" wrote in message
...
Thank you for quick replying .
It seems difficult to understand the exact meaning.
Any way , thanks to you, I succeeded in preventing from Excel starting.

"keepITcool" wrote in message
.com...

it's an identifier used for OLE and ATL.
i havent got any indepth knowledge of this.

personally i wouldn't fiddle with the bits
other than for testing and curiosity.



--
keepITcool
| www.XLsupport.com | keepITcool chello nl | amsterdam


Zoo wrote in

Thank you , keepITcool.
I changed the first 2 byte of a.ddd from D0 CF to 0D FC with a binary
editor as a test.
Then Excel.exe no more starts.

Can I as one more question?
Could you tell me the URL in which the meaning of the first 8 bytes
of biff8 is decribed?

"keepITcool" wrote in message
.com...

it first looks in the registry to see if it has a defined
application for that extension. if not it looks at the first 8
bytes in the file and recognizes it as biff8. (excel97-2003)


--
keepITcool
www.XLsupport.com | keepITcool chello nl | amsterdam


Zoo wrote in

I'm using Excel2002 on Windows2000.
I had a book whose name is a.xls.
And I changed its name to a.ddd in order not to start Excel.exe by
double clicking the file.
But double-clicking the file, Excel.exe starts.
How does Windows recognize the file as Excel's data file?

How does Windows recognize the file as Excel's?
 

Thank you Jeff.
As you have said, changing the file extension to .txt seems easier than
modifying the binary.
I will try that.

"Jeff Standen" wrote in message
...
But your problem is that the file probobly now won't work at all. Maybe
you
should change it to .txt or something instead of fiddling with the binary
data.

Jeff

"Zoo" wrote in message
...
Thank you for quick replying .
It seems difficult to understand the exact meaning.
Any way , thanks to you, I succeeded in preventing from Excel starting.

"keepITcool" wrote in message
.com...

it's an identifier used for OLE and ATL.
i havent got any indepth knowledge of this.

personally i wouldn't fiddle with the bits
other than for testing and curiosity.



--
keepITcool
| www.XLsupport.com | keepITcool chello nl | amsterdam


Zoo wrote in

Thank you , keepITcool.
I changed the first 2 byte of a.ddd from D0 CF to 0D FC with a binary
editor as a test.
Then Excel.exe no more starts.

Can I as one more question?
Could you tell me the URL in which the meaning of the first 8 bytes
of biff8 is decribed?

"keepITcool" wrote in message
.com...

it first looks in the registry to see if it has a defined
application for that extension. if not it looks at the first 8
bytes in the file and recognizes it as biff8. (excel97-2003)


--
keepITcool
www.XLsupport.com | keepITcool chello nl | amsterdam


Zoo wrote in

I'm using Excel2002 on Windows2000.
I had a book whose name is a.xls.
And I changed its name to a.ddd in order not to start Excel.exe
by
double clicking the file.
But double-clicking the file, Excel.exe starts.
How does Windows recognize the file as Excel's data file?