regex is lower-case

Author: HeidiSteen

articles/search/query-lucene-syntax.md

@@ -10,7 +10,7 @@ ms.service: azure-ai-search
 ms.custom:
   - ignite-2023
 ms.topic: concept-article
-ms.date: 09/19/2024
+ms.date: 12/11/2024
 ---
 
 # Lucene query syntax in Azure AI Search
@@ -136,9 +136,14 @@ The following example helps illustrate the differences. Suppose that there's a s
 
 ##  <a name="bkmk_regex"></a> Regular expression search
 
- A regular expression search finds a match based on patterns that are valid under Apache Lucene, as documented in the [RegExp class](https://lucene.apache.org/core/6_6_1/core/org/apache/lucene/util/automaton/RegExp.html). In Azure AI Search, a regular expression is enclosed between forward slashes `/`.
+A regular expression search finds a match based on patterns that are valid under Apache Lucene, as documented in the [RegExp class](https://lucene.apache.org/core/6_6_1/core/org/apache/lucene/util/automaton/RegExp.html). 
 
- For example, to find documents containing `motel` or `hotel`, specify `/[mh]otel/`. Regular expression searches are matched against single words.
+In Azure AI Search, a regular expression is:
+
+* Enclosed between forward slashes `/`
+* Lower-case only
+
+For example, to find documents containing `motel` or `hotel`, specify `/[mh]otel/`. Regular expression searches are matched against single words.
 
 Some tools and languages impose extra escape character requirements beyond the [escape rules](#escaping-special-characters) imposed by Azure AI Search. For JSON, strings that include a forward slash are escaped with a backward slash: `microsoft.com/azure/` becomes `search=/.*microsoft.com\/azure\/.*/` where `search=/.* <string-placeholder>.*/` sets up the regular expression, and `microsoft.com\/azure\/` is the string with an escaped forward slash.