2.1 Physical characteristics Handheld devices are characterized primarily by a limited display size. For purposes of this proposal, PDA-style displays are not included in this handheld device category, although the markup language proposed will be useful on those devices as well. Alphanumeric pagers have even fewer keys. Item selection is accomplished through numbered lists or using cursor keys to highlight a choice and then request an action on that item. Full 2-D cursor control through pointing devices such as touch pads, touch screens, roller balls, are rare.
Network bandwidth is usually low due to limitations of the network technology or simple economics.
All in the name of economics. While some devices do have large amounts of memory or processing power, these devices are the exception. Mass market and consumer-targeted devices will continue to have these constraints for many years. Because of the smaller displays and limited input, bandwidth, and resources, handheld devices must be viewed as distinctly different from typical PCs, workstations, and other common platforms found on the web today. The HTML document model can be considered to consist of structural idioms such as header, paragraphs, lists, tables and figures as well as rendering idioms such as margins, leading, font names and sizes.