Configure system id's for imported content for DITA 1.2

After you create a custom catalog, you need to edit the system id's that tell IXIA CCMS Desktop which DTDs to recognize when content is imported into the CMS. (This file does not determine the DOCTYPE of content that is created in the CMS; that is determined by the topic and map templates.)

In Repository/system/conf, check out and open systemid.xml.

When you import DITA content that you've created outside of the IXIA CCMS Desktop, the CMS looks at the DOCTYPE reference. If the reference is not one that is recognized by the CCMS Desktop (according to what is listed in systemid.xml), the CCMS Desktop automatically remaps it to whatever the topicdefault is (or mapdefault, if you're importing a map). By default, this file defines two public id's that are accepted as defaults to map to. The defaults out of the box are the IxiaDitabase.dtd and IxiaMap.dtd.

If you want your imported content to be remapped to your custom shell DTDs, it's critical to edit systemid.xml accordingly.
In the first line, change the value of mapdefault to the public identifier of CompanyMap.dtd, as shown.
```
<id mapdefault="-//COMPANY//DTD DITA Map//EN" topicdefault="-//IXIA//DTD IXIA DITA Composite//EN">
```
In the same line, change the value of topicdefault to the public identifier of CompanyDitabase.dtd, as shown.
```
<id mapdefault="-//COMPANY//DTD DITA Map//EN" topicdefault="-//COMPANY//DTD DITA Composite//EN">
```
In the first reference line, change the public identifier to the public identifier of CompanyDitabase.dtd, as shown.
```
<reference public="-//COMPANY//DTD DITA Composite//EN" system="IxiaDitabase.dtd"/>
```
You must have a reference for the DTD that you are using as the default.

Important: Note that you are replacing references to IxiaDitabase.dtd with references to the custom shell DTD in your plugin. Your shell completely takes the place of IxiaDitabase.dtd. This is unlike your custom catalog.xml, which does not replace, but adds to the functionality of the default catalog.xml file in the com.ixiasoft.dita.dtd plugin.
In that same line, change the system identifier path to reference CompanyDitabase.dtd, as shown.
```
<reference public="-//COMPANY//DTD DITA Composite//EN" system="CompanyDitabase.dtd"/>
```
Note: If you worked with systemid.xml in the past, you might notice that here, the system id is simply the file name without any path, whereas in previous releases, the system id included a relative path. This change does not have any effect on your content. XML editors use their own catalog settings to resolve DTDs and the DITA Open Toolkit is entirely catalog-based, so it does not use system id's at all.
In the second reference line, change the public identifier to the public identifier of CompanyMap.dtd, as shown.
```
<reference public="-//COMPANY//DTD DITA Map//EN" system="IxiaMap.dtd"/>
```
In that same line, change the system identifier path to reference CompanyMap.dtd, as shown.
```
<reference public="-//COMPANY//DTD DITA Map//EN" system="CompanyMap.dtd"/>
```
Save and check in systemid.xml.

The CCMS Desktop is now set up to recognize CompanyDitabase.dtd and CompanyMap.dtd when importing topics or maps.

Next, you need to edit the topic and map templates to include a DOCTYPE that references CompanyDitabase.dtdand CompanyMap.dtd.