fixed units
diff --git a/models/populations/org.eclipse.stem.ui.populationmodels/src/org/eclipse/stem/ui/populationmodels/standard/wizards/populationmodelwizardmessages.properties b/models/populations/org.eclipse.stem.ui.populationmodels/src/org/eclipse/stem/ui/populationmodels/standard/wizards/populationmodelwizardmessages.properties
index 7ee92cf..4e5a96a 100644
--- a/models/populations/org.eclipse.stem.ui.populationmodels/src/org/eclipse/stem/ui/populationmodels/standard/wizards/populationmodelwizardmessages.properties
+++ b/models/populations/org.eclipse.stem.ui.populationmodels/src/org/eclipse/stem/ui/populationmodels/standard/wizards/populationmodelwizardmessages.properties
@@ -24,15 +24,15 @@
 NPopulationWiz.DC_DESCRIPTION = Population Model "{0}"
 NPopulationInitializerWiz.DC_DESCRIPTION = Population Initializer "{0}"
 
-PMTP_Def = *PM/TP = Population Member/Time Period
+PMTP_Def = *[1/time] = Population Member/Time Period
 
 deathRate = Background Mortality Rate (\u03bc)
 deathRateTT = The rate at which population members die from causes other than the disease.
-deathRateUNIT = PM/TP*
+deathRateUNIT = [1/time]*
 
 birthRate = Background Birth Rate
 birthRateTT = The rate at which population members are born.
-birthRateUNIT = PM/TP*
+birthRateUNIT = [1/time]*
 
 populationIdentifier = Population
 populationIdentifierTT = The name of the population infected by this disease. (e.g., human)