These are the possible error conditions that are checked. Many of these conditions, and the wording of the corresponding message, are from the Microsoft XML parser. Others are specific to System Architect and XML Architect.

A symbol must have a name. You are not allowed to drop an unnamed symbol onto a diagram. You will receive a warning that the element must be named.

As soon as a symbol is dropped onto the diagram, it gets a name consisting of its type, a hyphen, and a unique number. You can overtype that name, and then press Enter. To change the name of an existing symbol, right‑click the symbol, and then click Symbol Rename.

If you have made customization to the tool (via USRPROPS.TXT) to get around the above behavior, and have symbols on a diagram with no name, running the Rules Check flags symbols without a name on the diagram with Error (2).

In System Architect and XML Architect, you work with diagrams, on which you draw symbols, that have underlying definitions. This rule flags any symbol that does not have an underlying definition: for example, the symbol was drawn on the diagram, but you never opened its definition dialog (by double-clicking the symbol or right-clicking it and choosing Edit).

A symbol must have an XML Schema. You are not allowed to create an XML diagram without specifying the schema the diagram represents.

For more information on defining XML Schemas, see XML schema.

This error flags the fact that an attribute symbol has an Attribute Type, but that Attribute Type is not defined.

To define the Attribute Type, open the attribute symbol’s definition dialog, click the Symbol tab, and then click Define under XML Attribute Type.

The name of a schema, an element, an attribute, or a group cannot start with the letters xml (in either upper case or lower case).

Symbol names cannot contain spaces between words. To rename a symbol without the extra space, select the symbol on an open diagram, right-mouse click, and select Symbol Rename. This will rename the symbol selected.

The name of a schema, an element, an attribute, or a group cannot start with a number.

The name of a schema, an element, or an attribute cannot start with the characters shown.

This error flags the fact that an element or an attribute has a data type of Enumeration but its Values property is empty.

See also Descriptions of data types.

This error flags the fact that an element or an attribute has a data type of Enumeration, and it has a list of Values, but the value specified in the Default property is not found in the list of Values.

See also Descriptions of data types.

If an attribute is required, it should not have a default value. This error flags the fact that in the attributes symbol properties, its Required property is set to Yes, but its Default property has a value.

You should either make the attribute not required, or delete the default value.

An enumeration is a set of values, for example, color = red, blue, indigo. This error flags the fact that you have a bad character in the element or attributes Values list. The following are considered bad characters: >, <, and &.

XML Schema documents provide a mechanism for defining enumerations to constrain attribute or element string content. In simpler terms, an enumeration is a set of values, for example, color = red, blue, indigo.

This error message flags the fact that the attributes Values property has values in it, but no data type is specified.

Select the data type enumeration.

This error flags an element with a data type, whose Content is NOT textOnly (i.e mixed, empty or eltOnly). If an element has a data type its Content must be set to textOnly.

Change the Content to textOnly if you want the data type, or remove the data type if the Content should not be textOnly.

This error flags the fact that the element's Content property is set to mixed, but its Order property is not set to many.

This error provides a warning that the Content property of an element is not one set to one of the values above.

Open the definition dialog of an element, and set the Content property to one of the above values.

There can be a number of XML Text Entities with the same name, but different schema, and perhaps different Text properties. The one Text Entity that gets checked is the one for the same schema as the symbol, or the one with the same schema as the diagram.

See also XML text entity (DTDs only).

This error flags the fact that an element’s Model property is not set to open or closed. The only way this error could occur is if you customized the tool (via USRPROPS.TXT) to add your own model type.

An enumeration is a set of values, for example, color = red, blue, indigo. This error flags the fact that in the definition of an attribute you have entered a set of values in the Values property, but have not set the attribute Type to Enumeration.

Either delete the values in the Values property of the attributes definition, or change the type of the attribute to Enumeration.

This error flags the fact that you have not set a Data Type for an attribute.

Open the attributes definition and click the Attribute tab. Select the Data Type from the drop down list. For more information on selecting data types, please see XML Attribute Type Properties.

This error provides a warning to the fact that an element or attribute has a data type that is not specified by a DTD. This error would occur if you typed in your own data type in the Data Type property of an element or attribute (or customized the tool to add new datatypes via USRPROPS.TXT, and then selected one of these new datatypes).

A group symbol must have at least one child element symbol. This error flags any group symbols on a diagram that do not have at least one element symbol attached as children beneath them.

This error flags the fact that in an element's definition, you have set the Content property to textOnly, but you have a group symbol attached as a child to this element symbol on the diagram. If an element is text only, it cannot have a group of child elements or attributes.

This error flags the fact that a group symbol is pictured on the diagram and is not connected as a child to a parent element symbol.

The group symbol is used to show a grouping of elements that have specific constraints against them. The group symbol is normally attached underneath an element, with the elements of the group attached beneath it.

This error flags the fact that there are child element or attribute symbols connected underneath an element symbol on the diagram, even though the Content property of the element's definition is set to textOnly.

This error flags the fact that there are child element or attribute symbols connected underneath an element symbol on the diagram, even though the Content property of the element's definition is set to empty.

This error flags the fact that there are child element symbols connected underneath an element symbol on the diagram, even though the Data Type property of the element's definition is set to a value.

Open the element symbol's definition dialog, select the Data Type property (to highlight the value in the box), and delete the value.

This error will occur if there are two attributes with the same name under a parent element. This situation can only be created by importing a file with this condition.

Rename one of the attributes.

This is a warning that there are more than one top-level (or root) element symbols on the diagram. A valid schema has only one root symbol.

Make sure you have a single top-level element to your hierarchy tree on a diagram. Examples of error conditions are if you have two or more trees, or if you have a tree and a single element symbol sits by itself unconnected to other symbols on the diagram.

This error flags the fact an attribute or group symbol sits at the top of a tree on a diagram. The top symbol of a tree must be an element symbol.

This error flags the fact an attribute symbol sits at the top of a tree (or sits by itself) on a diagram. An attribute symbol must report to a parent element symbol.

This warning flags the fact that then name of your schema starts with a number.

Comments for a symbol or definition cannot contain the string '--' (double-hyphen).

You will receive an Error(43) if:

Notice that in both cases, the symbol is displayed with a dashed border.

Open the symbol’s dialog and click the Definition tab. Select the Define button underneath the XML Schema property. Enter the schema’s path name or URL in the XML schema field.

An XML Element Entity or XML Attribute Entity must have a valid parent symbol.