--- a/configmix/config.py	Sun Aug 13 16:14:39 2023 +0200
+++ b/configmix/config.py	Mon Aug 14 09:31:27 2023 +0200
@@ -242,6 +242,7 @@
 _FILTER_SEPARATOR = u(b'|')
 _STARTTOK_REF = _STARTTOK + REF_NAMESPACE + _NS_SEPARATOR
 _ENDTOK_REF = _ENDTOK
+_ENDTOK_FILTER = _FILTER_SEPARATOR + _ENDTOK
 _DOT = u(b'.')
 _TILDE = u(b'~')
 _QUOTE = u(b'%')
@@ -1009,6 +1010,24 @@
                                    "%r (cached)" % (s, ))
                 else:
                     return res
+                
+        if ((len_s >= 6)
+                and (s[2] == _FILTER_SEPARATOR)
+                and (start == 0)):
+            if s.find(_ENDTOK_FILTER, 3) != (len_s - 3):
+                raise ValueError("`{{|' global filter interpolation must end with `|}}'")
+            new_s, filters = _split_filters(s[3:-3])
+            try:
+                varvalue = self.py_interpolate_variables(new_s)
+            except KeyError:
+                if NONE_FILTER in filters:
+                    varvalue = None
+                elif EMPTY_FILTER in filters:
+                    varvalue = _EMPTY_STR
+                else:
+                    raise
+            varvalue = self._apply_filters(filters, varvalue)
+            return varvalue
         res = []
         res_append = res.append
         rest = 0