diff --git a/grpc/pb/bdware/bdledger/api/query.proto b/grpc/pb/bdware/bdledger/api/query.proto
index 755e30e..be8795b 100644
--- a/grpc/pb/bdware/bdledger/api/query.proto
+++ b/grpc/pb/bdware/bdledger/api/query.proto
@@ -17,17 +17,31 @@ service Query {
   /**
    * Get blocks in a timestamp range
    * 查询时间范围内的区块
-   * start_timestamp is required
+   * Requirement: start_timestamp <= end_timestamp
+   * If neither 'start_timestamp' nor 'end_timestamp' is specified, then 'start_timestamp' will be set to
+   * the genesis block's timestamp, and 'end_timestamp' will be set to (start_timestamp + query.maxDuration)
+   * (query.maxDuration is specified in go-bdledger's config file).
+   * If only 'end_timestamp' is not specified, or (end_timestamp - start_timestamp > query.maxDuration),
+   * then 'end_timestamp' will be set to (start_timestamp + query.maxDuration).
+   * If only 'start_timestamp' is not specified, then 'start_timestamp' will be set to (end_timestamp - query.maxDuration).
+   * In all cases, 'start_timestamp' will never be earlier than the genesis block's timestamp,
+   * and 'end_timestamp' will never be later than the current timestamp when the node process the query request.
    */
   rpc GetBlocks (BlocksRequest) returns (GetBlocksResponse);
   /**
    * Count all blocks in a ledger, or blocks in a timestamp range
    * 查询帐本中的所有区块数量，或时间范围内的区块数量
+   * Requirement: start_timestamp <= end_timestamp
+   * If neither 'start_timestamp' nor 'end_timestamp' is specified, then count all blocks in the specified ledger.
+   * If only 'end_timestamp' is not specified, then count all blocks with timestamps later than 'start_timestamp'.
+   * If only 'start_timestamp' is not specified, then count all blocks with timestamps earlier than 'end_timestamp'.
+   * In all cases, 'start_timestamp' will never be earlier than the genesis block's timestamp,
+   * and 'end_timestamp' will never be later than the current timestamp when the node process the query request.
    */
   rpc CountBlocks (BlocksRequest) returns (CountBlocksResponse);
   /**
    * Get recent 'count' blocks (Only support IncludeTransactions=NONE for now)
-   * 查询最新的n个区块
+   * 查询最新的 'count' 个区块
    */
   rpc GetRecentBlocks (RecentBlocksRequest) returns (GetBlocksResponse);
   /**
@@ -43,12 +57,13 @@ service Query {
   /**
    * Get transactions in a timestamp range
    * 查询时间范围内的事务
+   * 'start_timestamp' and 'end_timestamp' follow the same requirements and rules as in 'GetBlocks'.
    */
   rpc GetTransactions (TransactionsRequest) returns (GetTransactionsResponse);
   /**
    * Count all transactions in a ledger, or transactions in a timestamp range
    * 查询帐本中的所有事务数量，或时间范围内的事务数量
-   * start_timestamp is required
+   * 'start_timestamp' and 'end_timestamp' follow the same requirements and rules as in 'CountBlocks'.
    */
   rpc CountTransactions (TransactionsRequest) returns (CountTransactionsResponse);
 }