diff --git a/reclass/datatypes/parameters.py b/reclass/datatypes/parameters.py
index fa53a7a..363e508 100644
--- a/reclass/datatypes/parameters.py
+++ b/reclass/datatypes/parameters.py
@@ -6,6 +6,8 @@
 # Copyright © 2007–13 martin f. krafft <madduck@madduck.net>
 # Released under the terms of the Artistic Licence 2.0
 #
+from reclass.defaults import PARAMETER_INTERPOLATION_DELIMITER
+
 class Parameters(object):
     '''
     A class to hold nested dictionaries with the following speciality:
@@ -21,7 +23,7 @@
     To support this speciality, this class only exposes very limited
     functionality and does not try to be a really mapping object.
     '''
-    DEFAULT_PATH_DELIMITER = ':'  # useful default for YAML
+    DEFAULT_PATH_DELIMITER = PARAMETER_INTERPOLATION_DELIMITER
 
     def __init__(self, mapping=None, delimiter=None):
         if delimiter is None:
diff --git a/reclass/defaults.py b/reclass/defaults.py
index 39142a5..7d2dfea 100644
--- a/reclass/defaults.py
+++ b/reclass/defaults.py
@@ -23,3 +23,6 @@
                            os.path.dirname(sys.argv[0])
                           ]
 CONFIG_FILE_NAME = RECLASS_NAME + '-config.yml'
+
+PARAMETER_INTERPOLATION_SENTINELS = ('${', '}')
+PARAMETER_INTERPOLATION_DELIMITER = ':'