diff --git a/parsers/survex.py b/parsers/survex.py
index cbc91bd..3f490ea 100644
--- a/parsers/survex.py
+++ b/parsers/survex.py
@@ -183,6 +183,10 @@ def RecursiveLoad(survexblock, survexfile, fin, textlines):
             survextitle = models.SurvexTitle(survexblock=survexblock, title=line.strip('"'), cave=survexblock.cave)
             survextitle.save()
             
+        elif cmd == "require":
+            # should we check survex version available for processing?
+            pass
+
         elif cmd == "data":
             ls = line.lower().split()
             stardata = { "type":ls[0] }
@@ -200,8 +204,10 @@ def RecursiveLoad(survexblock, survexfile, fin, textlines):
 
         elif cmd == "fix":
             survexblock.MakeSurvexStation(line.split()[0])
+
         else:
-            assert cmd in [ "sd", "include", "units", "entrance", "data", "flags", "title", "export", "instrument", "calibrate", "set", "infer"], (cmd, line, survexblock)
+            if not cmd in [ "sd", "include", "units", "entrance", "data", "flags", "title", "export", "instrument", "calibrate", "set", "infer", "alias" ]:
+                print ("Unrecognised command in line:", cmd, line, survexblock)