reference: UI Requirements for Mobile Devices

[pauric]

I posted a request for mobile UI guidelines on the Interaction
Designers mailing list.  Some great info in this post, I'm forwarding
it for anyone interested.

---------- Forwarded message ----------
Standards may be tough to find, as mobile phone interfaces are largely
proprietary to the handset manufacturer.  But I would recommend having
a look at the UI guidelines for some of the open mobile operating
systems that feature touchscreen:

1. iPhone Web Developers Guide:
http://developer.apple.com/iphone/designingcontent.html
2. Palm OS: http://www.access-company.com/developers/documents/docs/ui/UIGuide_Front.html
3. Windows Mobile (Pocket PC):
http://msdn2.microsoft.com/en-us/library/ms854763.aspx
4. UIQ (Sony Ericsson P900/910/990):
http://developer.uiq.com/devlib/uiq_30/SDKDocumentation/uiq/uiqstyleguide/index.html
5. Nokia Series 90 (Nokia 7700/ Nokia 7710):
http://www.forum.nokia.com/info/sw.nokia.com/id/775f4744-dedf-4f32-956d-815e02ba670d/Nokia_7710_UI_Style_Guide_v1_0_en.pdf.html

I have included a couple of specific references below to guidelines
for taps/ touches below.

<iPhone Web Developers Guide>

The following table lists the actions and results of using fingers as
an input device.

Double tap = Zoom in and center a block of content
Touch and hold = Display an information bubble
Drag = Move the viewport or pan
Flick = Scroll up or down (depending on the direction of the finger movement)
Pinch open = Zoom in
Pinch close = Zoom out

A few other things to keep in mind about fingers as an input device:
- There are no gestures to perform cut, copy, paste, drag-and-drop,
and text selection operations.
- The width of a finger limits the density of links on a page. If the
links are too close, your users won't be able to choose a single one.

</ iPhone Web Developers Guide>

<Palm OS UI Guidelines>

Minimize Taps
Most information about that data should be accessible in a minimal
number of taps of the stylus - one or two.

Desktop user interfaces are typically designed to display commands as
if they were used equally. In reality, some commands are used very
frequently while most are used only rarely. Similarly, some settings
are more likely to be used than others. On Palm Powered handhelds,
more frequently used
commands and settings should be easier to find and faster to execute.

* Frequently executed software commands should be accessible by one tap.

* Infrequently used or dangerous commands may require more user action.

Table 1.1 shows how the frequency of an action maps to its
accessibility in the Date Book application.

Table 1.1 Frequency of actions Frequency  Example  Accessibility
Several times per day Checking today's schedule or to-do items One tap
Several times per week Scheduling a one hour meeting starting at the
top of the hour One tap, write in place
A few times a month Setting a weekly meeting (repeating event) Several
taps, second dialog box

This goal of minimizing taps can be taken too far. It must be balanced
with other guidelines. For example, using a command button generally
minimizes the taps to perform a command, but if you have too many
buttons, you overcrowd the screen and introduce confusion into the
interface.

Some designers break the behavior guidelines for a particular element
for the sole purpose of minimizing taps. User interface elements
should behave the way users expect them to behave unless there is good
reason for them not to. Minimizing taps is not always a good enough
reason to break
guidelines.

</Palm OS UI Guidelines>