diff --git a/src/main.rs b/src/main.rs
index 93a3765..19be4f5 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -9,7 +9,7 @@ fn main() {
 }
 
 #[derive(Debug, PartialEq, Serialize, Deserialize)]
-struct Storage {
+struct TSheet {
    xs: Vec<X>,
 }
 
@@ -20,32 +20,32 @@ struct X {
    tag: String,
 }
 
-fn save_storage(path: String, storage: Storage) -> Result<(), String> {
+fn save(path: String, tsheet: TSheet) -> Result<(), String> {
    match File::create(path.clone()) {
-      Ok(mut writer) => _save_storage(&mut writer, storage),
-      Err(reason) => Err(format!("failed to open {} to save storage: {}", path, reason)),
+      Ok(mut writer) => _save(&mut writer, tsheet),
+      Err(reason) => Err(format!("failed to open {} to save tsheet: {}", path, reason)),
    }
 }
 
-fn _save_storage(writer: &mut dyn Write, storage: Storage) -> Result<(), String> {
+fn _save(writer: &mut dyn Write, tsheet: TSheet) -> Result<(), String> {
    let mut w = serde_yaml::Serializer::new(writer);
-   match storage.serialize(&mut w) {
+   match tsheet.serialize(&mut w) {
       Ok(_) => Ok(()),
-      Err(reason) => Err(format!("failed to serialize storage: {}", reason)),
+      Err(reason) => Err(format!("failed to serialize tsheet: {}", reason)),
    }
 }
 
-fn load_storage(path: String) -> Result<Storage, String> {
+fn load(path: String) -> Result<TSheet, String> {
    match File::open(path.clone()) {
-      Ok(mut reader) => _load_storage(&mut reader),
-      Err(reason) => Err(format!("failed to read storage {}: {}", path, reason)),
+      Ok(mut reader) => _load(&mut reader),
+      Err(reason) => Err(format!("failed to read tsheet {}: {}", path, reason)),
    }
 }
 
-fn _load_storage(reader: &mut dyn Read) -> Result<Storage, String> {
-   match serde_yaml::from_reader::<&mut dyn Read, Storage>(reader) {
-      Ok(storage) => Ok(storage),
-      Err(err) => Err(format!("failed to parse storage: {}", err)),
+fn _load(reader: &mut dyn Read) -> Result<TSheet, String> {
+   match serde_yaml::from_reader::<&mut dyn Read, TSheet>(reader) {
+      Ok(tsheet) => Ok(tsheet),
+      Err(err) => Err(format!("failed to parse tsheet: {}", err)),
    }
 }
 
@@ -55,34 +55,34 @@ mod test_save_load {
 
    #[test]
    fn test_save_load_empty() {
-      let got = _load_storage(&mut "xs: []".as_bytes()).expect("failed to parse 'xs: []' storage");
-      assert_eq!(got, Storage{xs: vec![]});
+      let got = _load(&mut "xs: []".as_bytes()).expect("failed to parse 'xs: []' tsheet");
+      assert_eq!(got, TSheet{xs: vec![]});
 
       let mut w = vec![];
-      _save_storage(&mut w, got).expect("failed saving storage to writer");
+      _save(&mut w, got).expect("failed saving tsheet to writer");
       assert_eq!(String::from_utf8(w).unwrap(), "xs: []\n".to_string());
    }
 
    #[test]
    fn test_testdata_standalone_yaml() {
-      let want = Storage{xs: vec![
+      let want = TSheet{xs: vec![
          X{t: 1, x: "def".to_string(), tag: "abc".to_string()},
          X{t: 2, x: "ghi".to_string(), tag: "".to_string()},
       ]};
       assert_eq!(
-         load_storage("./src/testdata/standalone.yaml".to_string()).expect("cant load standalone.yaml"),
+         load("./src/testdata/standalone.yaml".to_string()).expect("cant load standalone.yaml"),
          want,
       );
 
       let mut w = vec![];
-      _save_storage(&mut w, want).expect("failed saving storage to writer");
+      _save(&mut w, want).expect("failed saving tsheet to writer");
       assert_eq!(String::from_utf8(w).unwrap(), "xs:\n- t: 1\n  x: def\n  tag: abc\n- t: 2\n  x: ghi\n  tag: ''\n".to_string());
    }
 }
 
-impl Storage {
-   fn from(&self, t: SystemTime) -> Storage {
-      let mut result = Storage{xs: vec![]};
+impl TSheet {
+   fn from(&self, t: SystemTime) -> TSheet {
+      let mut result = TSheet{xs: vec![]};
       self.xs.iter()
          .filter(|x| x.ts() >= t)
          .for_each(|x| result.xs.push(x.clone()));
@@ -97,17 +97,17 @@ impl X {
 }
 
 #[cfg(test)]
-mod test_storage {
+mod test_tsheet {
    use super::*;
 
    #[test]
-   fn test_storage_from_date() {
-      let given = Storage{xs: vec![
+   fn test_tsheet_from_date() {
+      let given = TSheet{xs: vec![
          X{t: 1, x: "def".to_string(), tag: "abc".to_string()},
          X{t: 2, x: "ghi".to_string(), tag: "".to_string()},
          X{t: 3, x: "jkl".to_string(), tag: "".to_string()},
       ]};
-      let want = Storage{xs: vec![
+      let want = TSheet{xs: vec![
          X{t: 2, x: "ghi".to_string(), tag: "".to_string()},
          X{t: 3, x: "jkl".to_string(), tag: "".to_string()},
       ]};