hyperlinks

[Guest]

How many hyperlinks can you put in a ppt 2000. If you copy and paste the
same hyperlink on another slide does ppt count this as an extra hyperlink?

Thanks

 

[Guest]

There is no specific number of hyperlinks. Instead, there is a limited amount
of space set aside for hyperlinks. I believe the size of the space is 32K (I
believe Steve Rindsberg explained it recently as a 64K block of space that
already has a 32K brick in it). This means that hyperlinks to longer
addresses will take up more space, and you can squeeze a few extra links out
of the space by making the links shorter (reducing the size of the path,
reducing the number of characters in the file name, linking to a reduced-size
URL from tinyurl.com instead of the full URL, limiting the number of
characters in the title of a slide being linked to, etc.). I do not believe
that copy/pasted hyperlinks will save you anything over simply redoing the
hyperlinks, but I'm not sure about that.
--David

David Marcovitz
Microsoft PowerPoint MVP
Author of _Powerful PowerPoint for Educators_
http://www.loyola.edu/education/PowerfulPowerPoint/

 

[Steve Rindsberg]

There is no specific number of hyperlinks. Instead, there is a limited amount
of space set aside for hyperlinks. I believe the size of the space is 32K (I
believe Steve Rindsberg explained it recently as a 64K block of space that
already has a 32K brick in it).

That's the ticket. But MS suggests that that 32k may hold other things as well,
so we don't know that it's all available for hyperlinks.

This means that hyperlinks to longer
addresses will take up more space, and you can squeeze a few extra links out
of the space by making the links shorter (reducing the size of the path,
reducing the number of characters in the file name, linking to a reduced-size
URL from tinyurl.com instead of the full URL, limiting the number of
characters in the title of a slide being linked to, etc.). I do not believe
that copy/pasted hyperlinks will save you anything over simply redoing the
hyperlinks, but I'm not sure about that.

Nor I, but I'm betting with you. Hyperlinks on the slide master/title master
should only be counted once, though.

 

[Guest]

Thank you for this. What if the hyperlinks are links to pages in the same
presentation, say in a menu page. The menu page has a navigation bar which
is copy and pasted throughout the presentation. This means it looks like a
website but in reality every page has the same menu and hypelinks. Does
PowerPoint count every hyperlink in everypage as a new one even though it is
copy and pasted?

Thanks

 

[David M. Marcovitz]

In that case, put the menu on the master slide so it appears on every
slide. Then, it will only be counted once. If there are some slides that
shouldn't have the menu buttons, you can either use multiple masters
(2002 and 2003 only) or cover up the buttons on those few slides.
However, if you are concerned about running out of hyperlink space and
almost every slide has the buttons, you definitely want to put the
buttons on the master.
--David

--
David M. Marcovitz
Microsoft PowerPoint MVP
Director of Graduate Programs in Educational Technology
Loyola College in Maryland
Author of _Powerful PowerPoint for Educators_
http://www.loyola.edu/education/PowerfulPowerPoint/

 

[Chris Nokleberg]

That's the ticket. But MS suggests that that 32k may hold other things as well,
so we don't know that it's all available for hyperlinks.

The specification for how hyperlinks are stored in the
DocumentSummaryInformation stream is available here:

http://msdn.microsoft.com/archive/en-us/dnaro97ta/html/msdn_hyper97.asp

It works out to around 48 bytes per hyperlink, plus the bytes for
the actual Address and SubAddress text.

The number of bytes that the link text takes up depends on the codepage
used to save the property set. Microsoft recommends that Unicode be used
wherever possible, for interoperability. In this case each character will
take up two bytes, plus two for the trailing null. I'm not sure PowerPoint
follows this recommendation, though, as it often uses the native codepage
(e.g. Windows ANSI 1252).

The maximum size for a property set stream like DocumentSummaryInformation
is defined to be 256K. I'm not sure where the 32K or 64K number comes
from, but it may reflect some implementation-specific limit in the current
version of Windows or Office.

As for the "other things" stored alongside the hyperlinks, a full list of
the elements of the DocumentSummaryInformation is available here:

http://msdn.microsoft.com/library/e...information_and_userdefined_property_sets.asp

All user-defined ("custom") properties are stored here, but I don't they
are used all that much. The thing which probably takes up the most space
is the HeadingPairs/TitlesOfParts stuff, which makes up what you see in
the "Contents" tab of the Properties dialog under the PowerPoint File
menu. This includes a list of all the slide titles. Which means that if
you shorten or remove your slide titles you will make more room for
hyperlinks.

Chris Nokleberg

Tonic Systems, Inc.
http://tonicsystems.com/

 

[Echo S]

Wow.

is defined to be 256K. I'm not sure where the 32K or 64K number comes

http://support.microsoft.com/?scid=kb;EN-US;Q249209

 

[Steve Rindsberg]

Thank you for this. What if the hyperlinks are links to pages in the same
presentation, say in a menu page. The menu page has a navigation bar which
is copy and pasted throughout the presentation. This means it looks like a
website but in reality every page has the same menu and hypelinks. Does
PowerPoint count every hyperlink in everypage as a new one even though it is
copy and pasted?

What David said. Exactly.

 

[Steve Rindsberg]

Chris, thanks very much for the info you've posted.

The specification for how hyperlinks are stored in the
DocumentSummaryInformation stream is available here:

http://msdn.microsoft.com/archive/en-us/dnaro97ta/html/msdn_hyper97.asp

It works out to around 48 bytes per hyperlink, plus the bytes for
the actual Address and SubAddress text.

Plus the pad bytes (the link info is dword aligned, which I assume means "padded to the nearest
multiple of 8 bytes)

The number of bytes that the link text takes up depends on the codepage
used to save the property set. Microsoft recommends that Unicode be used
wherever possible, for interoperability. In this case each character will
take up two bytes, plus two for the trailing null. I'm not sure PowerPoint
follows this recommendation, though, as it often uses the native codepage
(e.g. Windows ANSI 1252).

I'm not sure what it's doing, but if you create a title that includes characters well above 256
(say, using Arial Unicode), you get a mix of high numbers and negative numbers when you view
AscW(Mid$(.SubAddress,x,1))

The maximum size for a property set stream like DocumentSummaryInformation
is defined to be 256K. I'm not sure where the 32K or 64K number comes
from, but it may reflect some implementation-specific limit in the current
version of Windows or Office.

That's where the mystery keeps raising its head. See this for more info:
http://support.microsoft.com/?scid=kb;EN-US;Q249209

The salient bit is:

"PowerPoint stores the hyperlink information in the Document Summary storage area of the
presentation. This storage area has a limit of 64 KB. The Document Summary storage contains all
the document properties, custom properties, references, and other similar data.

Because the Document Summary storage is used by different aspects of the presentation, there is
a finite number of hyperlinks that can be stored in presentation. This is compounded by the
fact that the longer the text is for a hyperlink that you have to store, the fewer you can
store.

Theoretically you can store upward of 32 KB of characters in the Document Summary, which
translates to approximately 6,500 words. More than half of this is already allocated to
dedicated Document Summary items. After the free space is used, no more can be allocated to the
presentation"

So 32kb LESS whatever "more than half" means; and it's a bit vague on "different aspects of the
presentation". Possibly something other than hyperlinks and Doc Properties is stored here?

As for the "other things" stored alongside the hyperlinks, a full list of
the elements of the DocumentSummaryInformation is available here:

http://msdn.microsoft.com/library/en-us/stg/stg/the_documentsummaryinformation_and_userdefined_
property_sets.asp

All user-defined ("custom") properties are stored here, but I don't they
are used all that much. The thing which probably takes up the most space
is the HeadingPairs/TitlesOfParts stuff, which makes up what you see in
the "Contents" tab of the Properties dialog under the PowerPoint File
menu. This includes a list of all the slide titles. Which means that if
you shorten or remove your slide titles you will make more room for
hyperlinks.

Very definitely.

 

[Chris Nokleberg]

Plus the pad bytes (the link info is dword aligned, which I assume means "padded to the nearest
multiple of 8 bytes)

A DWORD is 4 bytes, but otherwise you are correct.

I'm not sure what it's doing, but if you create a title that includes characters well above 256
(say, using Arial Unicode), you get a mix of high numbers and negative numbers when you view
AscW(Mid$(.SubAddress,x,1))

I just realized that the hyperlink strings are type VT_LPWSTR, which means
they are always saved as Unicode, regardless of the codepage. The codepage
setting will still affect other strings stored in the
DocumentSummaryInformation, such as the Contents data, which will affect
the number of hyperlinks you can store.

That's where the mystery keeps raising its head. See this for more info:
http://support.microsoft.com/?scid=kb;EN-US;Q249209

Just for reference, the 256K limit is documented here:

http://msdn.microsoft.com/library/e...ed_storage_serialized_property_set_format.asp

This limit applies to all property sets, of which the
SummaryInformation and DocumentSummaryInformation streams are two
examples. My guess is that in practice there may be a lower limit due to
Microsoft's implementation. I'd be happy to find some more authoritative
document (that KB article is a little hand-wavy).

So 32kb LESS whatever "more than half" means; and it's a bit vague on
"different aspects of the presentation". Possibly something other than
hyperlinks and Doc Properties is stored here?

I haven't seen examples of anything else. The format is
well-documented (relative to most Microsoft file formats) and so it isn't
too hard to enumerate exactly what is in each stream.

If someone has an example presentation where they know that adding exactly
one additional hyperlink will corrupt it, I could help narrow down what
the real limit is. BTW, I'm pretty sure Microsoft could add a
warning dialog when you save a presentation that said something to the
effect of "you are about to corrupt your hyperlinks".

Chris Nokleberg

Tonic Systems, Inc.
http://tonicsystems.com/

 

[Echo S]

the real limit is. BTW, I'm pretty sure Microsoft could add a
warning dialog when you save a presentation that said something to the
effect of "you are about to corrupt your hyperlinks".

Oh, man, that would be way cool.

 

[Steve Rindsberg]

A DWORD is 4 bytes, but otherwise you are correct.

oops, thanks.

examples. My guess is that in practice there may be a lower limit due to
Microsoft's implementation. I'd be happy to find some more authoritative
document (that KB article is a little hand-wavy).

;-) I like the image. Yes.