text: import mongoose from 'mongoose';
  
  const ConversionXrefSchema = new mongoose.Schema({
    field_name: {
      type: String,
      required: true,
      index: true
    },
    val_from: {
      type: String,
      required: true,
      index: true
    },
    val_to: {
      type: String,
      required: true,
      index: true
    }
  });
  
  export default mongoose.model(
    'ConversionXref',
    ConversionXrefSchema,
    'conversion_xref'
  );
  