# Compiled Transform Overview

The compiled transform process takes all XSLT files, including referenced or included files, and compiles them into a DLL for improved performance. This method significantly enhances the efficiency of XSLT transformations but requires careful handling to avoid HTML structural issues.

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## Important Considerations

There are a few key nuances when working with compiled transforms, particularly regarding how they handle self-closing HTML tags.

### Example

HTML like this:

``` html 
<div></div>  
```

can be compiled into this:

``` html   
<div/>  
```

This can break the structure of your HTML. To prevent this, ensure that your XSLT compensates for empty tags by inserting a space. You can resolve this by using one of the following methods:

### Solutions

1. **Non-Breaking Space**  
``` html  
<div>&#160;</div>  
```

2. **Explicit Space**  
``` html  
<div><xsl:text> </xsl:text></div>  
```

Both of these will compile as:

``` html  
<div> </div>  
```

and will prevent issues with malformed HTML.

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## Testing Best Practices

Before deploying any XSLT changes, ensure thorough local testing. This is especially important for changes made in the `/ewcommon` or `/ptn` directories. Test these in **compiled mode** before going live.

### What to Check

1. **View Source Code:**  
   Look for occurrences of `/>` in your HTML output.

2. **Safe Tags:**  
   Tags like `<img/>` and `<br/>` are fine as self-closing tags. However, other self-closing tags may indicate a problem and need fixing.

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## Recompiling Steps

To recompile XSLTs, follow these steps:

1. In `protean.web.config`, locate the `compiledTransform` setting and set it to **off**.
2. Touch the `web.config` file to restart the app.
3. Navigate to the `/xsltc` folder and delete all its contents.
4. Go back to `protean.web.config` and set the `compiledTransform` setting to **on**.
5. Touch the `web.config` file again to restart the app.
6. Optionally, run a rebundle for good measure.

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## Recompiling Locally

When testing locally, you can force a recompile by appending `/?recompile=true` to your URL. However, be aware that this will revert back to the original XSLT when the app pool is reset, so avoid using this method on live environments.

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- [Back to XSLT Guide](/Front-End-Developer-Guide/v5/XSLT-Guide)

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