let mut allocated: Vec<HashMap<u128, u128>> = vec![HashMap::new(); tx.output.len()];

    if let Some(runestone) = runestone {
      // Determine if this runestone conains a valid issuance
      let mut allocation = match runestone.etching {
        Some(etching) => {
          // If the issuance symbol is already taken, the issuance is ignored
          if etching.rune < self.minimum || self.rune_to_id.get(etching.rune.0)?.is_some() {
            None
          } else {
            let (limit, term) = match (etching.limit, etching.term) {
              (None, Some(term)) => (Some(runes::MAX_LIMIT), Some(term)),
              (limit, term) => (limit, term),
            };

            // Construct an allocation, representing the new runes that may be
            // allocated. Beware: Because it would require constructing a block
            // with 2**16 + 1 transactions, there is no test that checks that
            // an eching in a transaction with an out-of-bounds index is
            // ignored.
            match u16::try_from(index) {