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diff --git a/modules/extensions_framework/validate.py b/modules/extensions_framework/validate.py
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+# -*- coding: utf8 -*-
+#
+# ***** BEGIN GPL LICENSE BLOCK *****
+#
+# --------------------------------------------------------------------------
+# Blender 2.5 Extensions Framework
+# --------------------------------------------------------------------------
+#
+# Authors:
+# Doug Hammond
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, see <http://www.gnu.org/licenses/>.
+#
+# ***** END GPL LICENCE BLOCK *****
+#
+"""
+Pure logic and validation class.
+
+By using a Subject object, and a dict of described logic tests, it
+is possible to arrive at a True or False result for various purposes:
+1. Data validation
+2. UI control visibility
+
+A Subject can be any object whose members are readable with getattr() :
+class Subject(object):
+	a = 0
+	b = 1
+	c = 'foo'
+	d = True
+	e = False
+	f = 8
+	g = 'bar'
+
+
+Tests are described thus:
+
+Use the special list types Logic_AND and Logic_OR to describe
+combinations of values and other members. Use Logic_Operator for
+numerical comparison.
+
+With regards to Subject, each of these evaluate to True:
+TESTA = {
+	'a': 0,
+	'c': Logic_OR([ 'foo', 'bar' ]),
+	'd': Logic_AND([True, True]),
+	'f': Logic_AND([8, {'b': 1}]),
+	'e': {'b': Logic_Operator({'gte':1, 'lt':3}) },
+	'g': Logic_OR([ 'baz', Logic_AND([{'b': 1}, {'f': 8}]) ])
+}
+
+With regards to Subject, each of these evaluate to False:
+TESTB = {
+	'a': 'foo',
+	'c': Logic_OR([ 'bar', 'baz' ]),
+	'd': Logic_AND([ True, 'foo' ]),
+	'f': Logic_AND([9, {'b': 1}]),
+	'e': {'b': Logic_Operator({'gte':-10, 'lt': 1}) },
+	'g': Logic_OR([ 'baz', Logic_AND([{'b':0}, {'f': 8}]) ])
+}
+
+With regards to Subject, this test is invalid
+TESTC = {
+	'n': 0
+}
+
+Tests are executed thus:
+S = Subject()
+L = Logician(S)
+L.execute(TESTA)
+
+"""
+
+class Logic_AND(list):
+	pass
+class Logic_OR(list):
+	pass
+class Logic_Operator(dict):
+	pass
+
+class Logician(object):
+	"""Given a subject and a dict that describes tests to perform on
+	its members, this class will evaluate True or False results for
+	each member/test pair. See the examples below for test syntax.
+	
+	"""
+
+	subject = None
+	def __init__(self, subject):
+		self.subject = subject 
+
+	def get_member(self, member_name):
+		"""Get a member value from the subject object. Raise exception
+		if subject is None or member not found.
+		
+		"""
+		if self.subject is None:
+			raise Exception('Cannot run tests on a subject which is None')
+		
+		return getattr(self.subject, member_name)
+
+	def test_logic(self, member, logic, operator='eq'):
+		"""Find the type of test to run on member, and perform that test"""
+		
+		if type(logic) is dict:
+			return self.test_dict(member, logic)
+		elif type(logic) is Logic_AND:
+			return self.test_and(member, logic)
+		elif type(logic) is Logic_OR:
+			return self.test_or(member, logic)
+		elif type(logic) is Logic_Operator:
+			return self.test_operator(member, logic)
+		else:
+			# compare the value, I think using Logic_Operator() here
+			# allows completeness in test_operator(), but I can't put
+			# my finger on why for the minute
+			return self.test_operator(member,
+				Logic_Operator({operator: logic}))
+
+	def test_operator(self, member, value):
+		"""Execute the operators contained within value and expect that
+		ALL operators are True
+		
+		"""
+		
+		# something in this method is incomplete, what if operand is
+		# a dict, Logic_AND, Logic_OR or another Logic_Operator ?
+		# Do those constructs even make any sense ?
+		
+		result = True
+		for operator, operand in value.items():
+			operator = operator.lower().strip()
+			if operator in ['eq', '==']:
+				result &= member==operand
+			if operator in ['not', '!=']:
+				result &= member!=operand
+			if operator in ['lt', '<']:
+				result &= member<operand
+			if operator in ['lte', '<=']:
+				result &= member<=operand
+			if operator in ['gt', '>']:
+				result &= member>operand
+			if operator in ['gte', '>=']:
+				result &= member>=operand
+			if operator in ['and', '&']:
+				result &= member&operand
+			if operator in ['or', '|']:
+				result &= member|operand
+			if operator in ['len']:
+				result &= len(member)==operand
+			# I can think of some more, but they're probably not useful.
+		
+		return result
+
+	def test_or(self, member, logic):
+		"""Member is a value, logic is a set of values, ANY of which
+		can be True
+		
+		"""
+		result = False
+		for test in logic:
+			result |= self.test_logic(member, test)
+
+		return result
+
+	def test_and(self, member, logic):
+		"""Member is a value, logic is a list of values, ALL of which
+		must be True
+		
+		"""
+		result = True
+		for test in logic:
+			result &= self.test_logic(member, test)
+		
+		return result
+
+	def test_dict(self, member, logic):
+		"""Member is a value, logic is a dict of other members to
+		compare to. All other member tests must be True
+		
+		"""
+		result = True
+		for other_member, test in logic.items():
+			result &= self.test_logic(self.get_member(other_member), test)
+		
+		return result
+
+	def execute(self, test):
+		"""Subject is an object, test is a dict of {member: test} pairs
+		to perform on subject's members. Wach key in test is a member
+		of subject.
+		
+		"""
+		
+		for member_name, logic in test.items():
+			result = self.test_logic(self.get_member(member_name), logic)
+			print('member %s is %s' % (member_name, result))
+
+# A couple of name aliases			
+class Validation(Logician):
+	pass
+class Visibility(Logician):
+	pass