Overview of HDML syntax

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Current chapter: Introduction to HDML
Section 8 out of 67 total sections , Section 2 out of 7 sections in this chapter

Overview of HDML syntax

This section provides a brief overview of HDML syntax. For a more complete description of HDML syntax and detailed reference information on the HDML language, see the HDML Language Reference provided with the UP.SDK.

Like HTML, HDML uses the printable 8-bit character set. The UP.Link ignores the case of HDML keywords¹. It also converts one or more contiguous newlines, carriage returns, tabs, or spaces to a single space. The HDML examples in this manual are formatted with newlines and tabs to make them easier to read. However, this formatting is not required for the HDML to be valid. In fact, the UP.Link removes it before sending the HDML to the phone.

Comments

HDML allows you to include comments, which the UP.Phone ignores. A comment begins with <-- and ends with -->. For example, the following is a comment:

... <-- This is a comment --> ...

Structure

The smallest unit of HDML your service can send to an UP.Link server is a single <HDML> statement or deck². The high-level syntax for the <HDML> statement is:

<HDML VERSION=version_num deck_options> actions cards </HDML>³ Element Meaning VERSION=version_num Specifies the HDML version number, such as 3.0. This option is required. deck_options Specify options that modify how the phone handles the deck. These options are described in more detail in the HDML Language Reference. actions Specify actions associated with phone function keys while the deck is loaded in the phone. These actions include tasks such as requesting another deck or card. cards Include one or more <DISPLAY>, <NODISPLAY>, <CHOICE>, or <ENTRY> statements that define individual cards.

Element	Meaning
`VERSION=version_num`	Specifies the HDML version number, such as 3.0. This option is required.
`deck_options`	Specify options that modify how the phone handles the deck. These options are described in more detail in the HDML Language Reference.
`actions`	Specify actions associated with phone function keys while the deck is loaded in the phone. These actions include tasks such as requesting another deck or card.
`cards`	Include one or more `<DISPLAY>`, `<NODISPLAY>`, `<CHOICE>`, or `<ENTRY>` statements that define individual cards.

Options

Many HDML statements allow you to specify options. Options appear before the closing angle bracket of a statement header and have the following syntax:

option1=value1 option2=value2 option3=value3 ...

Each option-value pair is separated by white space (tab, newline, carriage return, or space characters). It is recommended that you enclose all option values in single or double quotation marks (") or ('). If an option value contains spaces, quotation marks are required.

White space characters are not allowed between the option, the equal sign, and the value. For a complete list of the available options for an HDML statement, see the HDML Language Reference.

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Current chapter: Introduction to HDML
Section 8 out of 67 total sections , Section 2 out of 7 sections in this chapter

¹ Case does matter for HDML variable names, which you specify.
² Chapters later in this manual describe how to use digests, which allow your service to package multiple HDML statements (decks) in a single HTTP response.
³ This manual uses the following style conventions in syntax statements: HDML keywords are uppercase and appear in bold; placeholders that you replace with your own text appear in italic; optional keywords appear in italic bold.
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