How does Windows recognize the file as Excel's?

Zoo · 05-31-2006, 10:40 PM

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?

keepITcool · 06-01-2006, 01:50 AM

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 <news:<[email protected]>

> 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?

Zoo · 06-01-2006, 02:30 AM

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" <[email protected]> wrote in message
news:[email protected]...
>
> 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 <news:<[email protected]>
>
> > 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?

keepITcool · 06-01-2006, 03:00 AM

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 <news:<[email protected]>

> 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" <[email protected]> wrote in message
> news:[email protected]...
> >
> > 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 <news:<[email protected]>
> >
> > > 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?

Zoo · 06-01-2006, 03:30 AM

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" <[email protected]> wrote in message
news:[email protected]...
>
> 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 <news:<[email protected]>
>
> > 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" <[email protected]> wrote in message
> > news:[email protected]...
> > >
> > > 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 <news:<[email protected]>
> > >
> > > > 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?

Jeff Standen · 06-01-2006, 05:25 AM

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" <[email protected]> wrote in message
news:[email protected]...
> 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" <[email protected]> wrote in message
> news:[email protected]...
>>
>> 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 <news:<[email protected]>
>>
>> > 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" <[email protected]> wrote in message
>> > news:[email protected]...
>> > >
>> > > 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 <news:<[email protected]>
>> > >
>> > > > 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?
>

Zoo · 06-02-2006, 03:55 AM

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" <[email protected]> wrote in message
news:%[email protected]...
> 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" <[email protected]> wrote in message
> news:[email protected]...
> > 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" <[email protected]> wrote in message
> > news:[email protected]...
> >>
> >> 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 <news:<[email protected]>
> >>
> >> > 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" <[email protected]> wrote in message
> >> > news:[email protected]...
> >> > >
> >> > > 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 <news:<[email protected]>
> >> > >
> >> > > > 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?
> >
>
>