if you go here
You will see many .xml files which are where snippets are saved.
For merging html and php snippets there are two ways
Just open html.xml file and copy all the snippets in the php.xml one.
1. you need root privileges for editing php.xml
2.just copy nodes marked as <snippet> such as this
gksudo gedit php.xml
do not copy the root tag <snippets language="HTML"> and its closing counterpart </snippets> at the end of the file
<text><![CDATA[<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
<description>HTML — 4.01 Strict</description>
1. make a copy of the original html.xml file and rename it i.e. html-for-php.xml
2. in the copy change the attribute in the root snippets tag so this
if you restart gedit it will read both php.xml and html-for-php.xml files as snippet repositories for .php files
Sorry, I came here after a Google search which brought me to an Archive page for this topic and I am new t this forum, so I didn't see that Kane77 had already answered the question.