Update central-asia-seismic-vulnerability-curves.md

_datasets/central-asia-seismic-vulnerability-curves.md

@@ -25,7 +25,7 @@ purpose: Regional risk modelling. These data have been derived on a regional sca
   detailed history and hazard information is required to perform such hazard and risk
   modelling, particularly were applied to dimension mitigation structures or strategies
 resources:
-- coordinate_system: null
+- coordinate_system: None
   description: This file (available as JSON via API) contains four sheets named "Residential",
     "Non-residential", "Infrastructure" and "Human Loss". In each sheet column A defines
     the IM values in terms of PGA [g] and the vulnerability class is defined in the