Hello, in the config of a tool I want to integrate into Galaxy I would like to have a parameter with the following properties: <param name="var" type="integer" label="Var" value="50" optional="true" min="10" max="100" /> So it should be possible to leave this field empty, but when you choose to enter a number it should be between 10 and 100. The problem now is that Galaxy refuses to accept it when this field is empty. After encountering this problem I tried to solve the issue within Cheetah and tried the following: #if $var.value < 10 or $var.value > 100 #set $var.value = "" #end if Galaxy however throws the following error when loading the tool: galaxy.tools ERROR 2011-07-04 14:04:14,231 error reading tool from path: path/to/tool.xml Traceback (most recent call last): File "/galaxy/galaxy_server/lib/galaxy/tools/__init__.py", line 77, in load_tool tool = self.load_tool( os.path.join( self.tool_root_dir, path ) ) File "/galaxy/galaxy_server/lib/galaxy/tools/__init__.py", line 131, in load_tool tree = util.parse_xml( config_file ) File "/galaxy/galaxy_server/lib/galaxy/util/__init__.py", line 104, in parse_xml tree = ElementTree.parse(fname) File "/galaxy/galaxy_server/eggs/elementtree-1.2.6_20050316-py2.6.egg/elementtree/ElementTree.py", line 859, in parse tree.parse(source, parser) File "/galaxy/galaxy_server/eggs/elementtree-1.2.6_20050316-py2.6.egg/elementtree/ElementTree.py", line 583, in parse parser.feed(data) File "/galaxy/galaxy_server/eggs/elementtree-1.2.6_20050316-py2.6.egg/elementtree/ElementTree.py", line 1242, in feed self._parser.Parse(data, 0) ExpatError: not well-formed (invalid token): line 230, column 21 The token it is complaining about is the <. I searched the Cheetah documentation and also Google but was not able to come up with a solution. Could anyone of you knowledgeable guys help me find a solution to this, please? I would be very grateful! Thanks in advance! Best regards, Sarah