ex.md

syntax = "proto3";

import "validate/validate.proto";

message Person {
  uint64 id    = 1 [(validate.rules).uint64.gt = 999];

  string email = 2 [(validate.rules).string.email = true];

  Location home = 4 [(validate.rules).message.required = true];

  message Location {
    double lat = 1 [(validate.rules).double = { gte: -90,  lte: 90 }];
    double lng = 2 [(validate.rules).double = { gte: -180, lte: 180 }];
  }
}