diff --git a/Cargo.lock b/Cargo.lock
index 90000fc..8ccc828 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -215,9 +215,9 @@ checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
 
 [[package]]
 name = "bitflags"
-version = "2.3.3"
+version = "2.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "630be753d4e58660abd17930c71b647fe46c27ea6b63cc59e1e3851406972e42"
+checksum = "b4682ae6287fcf752ecaabbfcc7b6f9b72aa33933dc23a554d853aea8eea8635"
 
 [[package]]
 name = "block-buffer"
@@ -330,6 +330,7 @@ dependencies = [
  "async-compression 0.4.1",
  "async-stream",
  "async_zip",
+ "bitflags 2.4.0",
  "fmmap",
  "futures",
  "futures-core",
@@ -1403,7 +1404,7 @@ version = "0.38.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0a962918ea88d644592894bc6dc55acc6c0956488adcebbfb6e273506b7fd6e5"
 dependencies = [
- "bitflags 2.3.3",
+ "bitflags 2.4.0",
  "errno 0.3.1",
  "libc",
  "linux-raw-sys 0.4.3",
diff --git a/lib/Cargo.toml b/lib/Cargo.toml
index ad81701..1feabaf 100644
--- a/lib/Cargo.toml
+++ b/lib/Cargo.toml
@@ -47,6 +47,7 @@ zstd = { version = "^0.12", default-features = false, optional = true }
 memmap = { version = "0.7.0", optional = true }
 pin-project = { version = "1.1.3", optional = true }
 postcard = { version = "1.0.6", default-features = false }
+bitflags = "2.4.0"
 
 [dev-dependencies]
 insta = { version = "1.31.0", features = ["yaml"] }
diff --git a/lib/src/questions.rs b/lib/src/questions.rs
index 29a0745..de96d11 100644
--- a/lib/src/questions.rs
+++ b/lib/src/questions.rs
@@ -1,32 +1,77 @@
 use serde_derive::{Deserialize, Serialize};
+use serde::ser::SerializeStruct;
 
-#[derive(Debug, Default, Clone, Serialize, Deserialize, PartialEq)]
+use bitflags::bitflags;
+
+bitflags! {
+    #[repr(transparent)]
+    #[derive(Default, Debug, Clone, Copy, PartialEq, Eq, Hash)]
+    pub struct BatchFlags: u16 {
+        const FILENAME = 1;
+        const DESCRIPTION = 1 << 1;
+        const AUTHOR = 1 << 2;
+        const COMMENT = 1 << 3;
+        const URL = 1 << 4;
+        const DATE = 1 << 5;
+        const PROCESSED = 1 << 6;
+        const REDACTED = 1 << 7;
+        const COPYRIGHT = 1 << 8;
+        const THEME = 1 << 9;
+        const KIND = 1 << 10;
+        const SOURCE = 1 << 11;
+        const RATING = 1 << 12;
+    }
+}
+
+bitflags! {
+    #[repr(transparent)]
+    #[derive(Default, Debug, Clone, Copy, PartialEq, Eq, Hash)]
+    pub struct QuestionFlags: u16 {
+        const NUM = 1;
+        const AUTHOR = 1 << 1;
+        const COMMENT = 1 << 2;
+        const COMMENT1 = 1 << 3;
+        const TOUR = 1 << 4;
+        const URL = 1 << 5;
+        const DATE = 1 << 6;
+        const PROCESSED_BY = 1 << 7;
+        const REDACTED_BY = 1 << 8;
+        const COPYRIGHT = 1 << 9;
+        const THEME = 1 << 10;
+        const KIND = 1 << 11;
+        const SOURCE = 1 << 12;
+        const RATING = 1 << 13;
+        const BATCH_INFO = 1 << 14;
+    }
+}
+
+#[derive(Debug, Default, Clone, Deserialize, PartialEq)]
 pub struct BatchInfo {
-    #[serde(default, skip_serializing_if = "String::is_empty")]
+    #[serde(default)]
     pub filename: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
+    #[serde(default)]
     pub description: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
+    #[serde(default)]
     pub author: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
+    #[serde(default)]
     pub comment: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
+    #[serde(default)]
     pub url: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
+    #[serde(default)]
     pub date: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
+    #[serde(default)]
     pub processed_by: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
+    #[serde(default)]
     pub redacted_by: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
+    #[serde(default)]
     pub copyright: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
+    #[serde(default)]
     pub theme: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
+    #[serde(default)]
     pub kind: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
+    #[serde(default)]
     pub source: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
+    #[serde(default)]
     pub rating: String,
 }
 
@@ -79,6 +124,56 @@ impl BatchInfo {
     }
 }
 
+macro_rules! count_string_fields {
+    (($self:ident, $flags:ident, $len:ident, $FlagsType:ident) <- {$($field:ident:$flag:ident),+} ) => {$(
+        $len += 1;
+        if !$self.$field.is_empty() {
+            $flags |= $FlagsType::$flag;
+        }
+    )+}
+}
+
+macro_rules! serialize_fields {
+    (($self:ident, $flags:ident, $state:ident, $FlagsType:ident) <- {$($field:ident:$flag:ident),+} ) => {$(
+        if $flags.intersects($FlagsType::$flag) {
+            $state.serialize_field(std::stringify!($field), &$self.$field)?;
+        } else {
+            $state.skip_field(std::stringify!($field))?;
+        }
+    )+}
+}
+
+impl serde::Serialize for BatchInfo {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        let is_human_readable = serializer.is_human_readable(); 
+        let mut flags: BatchFlags = Default::default();
+        let mut len = 1;
+
+        count_string_fields!((self, flags, len, BatchFlags) <- {
+            filename: FILENAME, description: DESCRIPTION, author: AUTHOR, comment: COMMENT, url: URL, date: DATE,
+            processed_by: PROCESSED, copyright: COPYRIGHT, theme: THEME, kind: KIND, source: SOURCE, rating: RATING
+        });
+
+        let mut state = serializer.serialize_struct("BatchInfo", len)?;
+        
+        if is_human_readable {
+            state.skip_field("_flags")?;
+        } else {
+            state.serialize_field("_flags", &flags.bits())?;
+        }
+
+        serialize_fields!((self, flags, state, BatchFlags) <- {
+            filename: FILENAME, description: DESCRIPTION, author: AUTHOR, comment: COMMENT, url: URL, date: DATE,
+            processed_by: PROCESSED, copyright: COPYRIGHT, theme: THEME, kind: KIND, source: SOURCE, rating: RATING
+        });
+
+        state.end()
+    }
+}
+
 #[cfg(any(feature = "convert", feature = "convert_async"))]
 pub mod convert_common {
     use super::{BatchInfo, Question};