diff --git a/include/science/libndtp/types.h b/include/science/libndtp/types.h
index e7e4458..2a16c86 100644
--- a/include/science/libndtp/types.h
+++ b/include/science/libndtp/types.h
@@ -22,9 +22,16 @@ struct ElectricalBroadbandData {
     std::vector<uint64_t> channel_data;
   };
 
+  // data signedness
   bool is_signed;
+
+  // bit width
   uint32_t bit_width;
+
+  // sample rate in Hz
   uint32_t sample_rate;
+
+  // first timestamp in microseconds
   uint64_t t0;
   std::vector<ChannelData> channels;
 
@@ -40,8 +47,13 @@ struct ElectricalBroadbandData {
  * BinnedSpiketrainData represents spike count data.
  */
 struct BinnedSpiketrainData {
+  // first timestamp in microseconds
   uint64_t t0;
+
+  // bin size in milliseconds
   uint8_t bin_size_ms;
+
+  // spike counts for a single bin for each channel
   std::vector<uint8_t> spike_counts;
 
   // Packs the data into a list of NDTP messages.