# Advanced Search

Snowray provides an advanced search option for Custom Code Systems, which can be invoked by pressing the <img src="https://content.gitbook.com/content/ecIrdZnsDkSPypTQNKj0/blobs/dJrJacuWFqcCvEyvvEc1/filter_icon.svg" alt="" data-size="line"> advanced filter icon in the search bar. This enables users to specify additional criteria to restrict their searches.

![Advanced Filter Search](https://content.gitbook.com/content/ecIrdZnsDkSPypTQNKj0/blobs/zUk7CAhMWbq8H7Ig4uPE/code_system_advanced_filter_search.png)

The `Status` can be filtered using the radio buttons, while the `ECL` filter requires typing in a valid query using an improved version of [SNOMED CT Expression Constraint Language](https://snomed.org/ecl) that allows any kind of identifier to be used, not just SCT IDs. A content assist, which can be activated by pressing `Ctrl` + `Space`, helps users to construct ECL queries easily.

{% hint style="info" %}
The ECL evaluation of non-SNOMED CT terminologies supports the following basic operators: `=`, `<`, `<<`, `<!`, `^`, `*`, `AND`, `OR`, `MINUS`
{% endhint %}

Once the required filters are specified, pressing ![](https://content.gitbook.com/content/ecIrdZnsDkSPypTQNKj0/blobs/kmxhjgSXJMhVDXPFcUCl/apply_filter_button.png)will update the tree only with the matching results as per the filters.&#x20;
