S57 Map XML Encoding Standards: Parsing the Association Between XML Format and Business Information

# 1. Introduction to S57 Maps

S57 maps, as a nautical chart data format, are widely used in the maritime domain. XML, as a general-purpose data storage format, has gradually been applied to the storage and exchange of S57 map data. This chapter will introduce an overview of S57 maps, explore the advantages of XML as a storage format for S57 map data, and the importance of XML encoding standards.

# 2. Review of XML Basics

XML (eXtensible Markup Language) is a language used for marking up the structure of electronic documents, possessing self-descriptiveness and extensibility. In the context of S57 map data, XML is widely used as a storage format. Below is a review of some XML basics:

### 2.1 Structure and Syntax of XML

XML documents are composed of tags, attributes, text, and comments, forming a certain structure. Tags include start tags, end tags, and self-closing tags, with the ability to nest. For example:

<person>
     <name>John</name>
     <age>30</age>
</person>

### 2.2 Concept of XML Namespace

XML namespaces are used to prevent element name conflicts by introducing namespace prefixes to distinguish elements under different namespaces. For example:

<svg xmlns="***">
     <circle cx="50" cy="50" r="20" fill="red" />
</svg>

### 2.3 Roles of XML Schema and DTD

XML Schema and DTD (Document Type Definition) are used to define the structure and constraints of XML documents. XML Schema is written in XML, possessing a powerful type system, whereas DTD is a declarative constraint language. For example:

<!-- XML Schema Example -->
<xs:element name="address" type="xs:string"/>

<!-- DTD Example -->
<!ELEMENT name (#PCDATA)>

This brief review of XML basics will significantly aid in understanding the XML encoding standards for S57 maps.

# 3. S57 Map XML Encoding Standards

In the XML representation of S57 map data, following certain encoding standards is crucial. These standards ensure the XML file has a clear structure, accurate data, and is convenient for parsing and processing. This chapter will focus on introducing the relevant content of S57 map XML encoding standards.

#### 3.1 Definition of XML File Header Information

When defining the XML representation of S57 map data, the first thing to pay attention to is the XML file header information. XML file headers typically include version information and encoding methods, for example:

<?xml version="1.0" encoding="UTF-8"?>

Here, the `version` attribute specifies the XML version, and the `encoding` attribute specifies the character encoding method of the document. This information is crucial for correctly parsing XML files.

#### 3.2 XML Representation of S57 Map Feature Data

In XML, elements can be used to represent feature data from S57 maps. Each feature usually corresponds to an XML element, containing its attributes and child elements. For instance, an XML element representing a water feature might have the following structure:

<waterElement>
     <name>Ocean</name>
     <area>1000000</area>
</waterElement>

Here, `waterElement` signifies a water feature, including `name` and `area` as child elements