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A longdesc (or "long description") file is used to describe images that are too complex to summarize in alt text. Rather than including the description in the CNXML markup, the full, detailed description is contained in a separate file that is linked from the media element. This allows you to describe the image in as much detail as necessary without needing to keep the description short. A longdesc file:
  • Can be any file type, though a basic text-only HTML file is most appropriate.
  • Can be loaded into a Connexions module like any other image or resource file.
  • Is not a replacement for alt text, but instead is a chance for the author to elaborate on alt text.
  • Is only necessary when the image is so complicated that an alt text description is not sufficient to describe it.
The following example shows how to link to a longdesc file titled earnings_report_desc.html : <media id="longdesc_example" alt="An earnings graph showing steady growth of 6% over the past two quarters."longdesc="earnings_report_desc.html"><image mime-type="image/png" src="earnings_report.png" /></media> In this example, earnings_report_desc.html would most likely be a simple text file describing the details of the chart, including the data points, overall trends, and any other relevant information. While the alt text describes "steady growth of 6% over the past two quarters," the longdesc file can talk about specific features of the chart, such as a dip that coincided with a recent merger or a spike that represented a major product release. A screen reader user would have the option of following this link in order to get a detailed understanding of the data that would otherwise be conveyed and understood by sighted users through visual information.
Remember, longdesc files are not common, and are usually only used when the media element contains important visual information that is too complex and/or detailed for alt text.

Captioned video and audio transcripts

Captioning is another important consideration when dealing with video content. Users who are hearing impaired may not be able to understand all of the information being conveyed in a video, limiting their access to the material being described. This can be addressed by submitting videos that are captioned, allowing those users to read along with the spoken materials. If you are not able to caption your videos, another option is to include audio transcripts of the materials as a module resource that can be easily accessed using a link. While there are no specific tools or standards for providing this type of content, the important thing to remember is to make it as easy as possible for as many people as possible to access the information you are trying to communicate.

You can read more about how Connexions addresses accessibility concerns in m17212 - Accessibility Features of Connexions .

Embedding media elements in your module


Once you've attached your multimedia files to your module, the next step is to embed the media files in your content. This can be done by using the <media> element.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Berger describes sociologists as concerned with
Mueller Reply
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Source:  OpenStax, Ideas and tools for improving connexions modules and collections. OpenStax CNX. Mar 22, 2010 Download for free at http://cnx.org/content/col11184/1.2
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