diff --git a/Source/Modules/ControllerModules/InputSignal.swift b/Source/Modules/ControllerModules/InputSignal.swift
index c972f704..a6f6a423 100644
--- a/Source/Modules/ControllerModules/InputSignal.swift
+++ b/Source/Modules/ControllerModules/InputSignal.swift
@@ -121,7 +121,7 @@ enum CharCode: UInt16 {
 }
 
 struct InputSignal: CustomStringConvertible {
-  private(set) var useVerticalMode: Bool
+  private(set) var isTypingVertical: Bool
   private(set) var inputText: String?
   private(set) var inputTextIgnoringModifiers: String?
   private(set) var charCode: UInt16
@@ -133,12 +133,12 @@ struct InputSignal: CustomStringConvertible {
   private var extraChooseCandidateKey: KeyCode = .kNone
   private var extraChooseCandidateKeyReverse: KeyCode = .kNone
   private var absorbedArrowKey: KeyCode = .kNone
-  private var verticalModeOnlyChooseCandidateKey: KeyCode = .kNone
+  private var verticalTypingOnlyChooseCandidateKey: KeyCode = .kNone
   private(set) var emacsKey: vChewingEmacsKey
 
   public init(
     inputText: String?, keyCode: UInt16, charCode: UInt16, flags: NSEvent.ModifierFlags,
-    isVerticalMode: Bool, inputTextIgnoringModifiers: String? = nil
+    isVerticalTyping: Bool, inputTextIgnoringModifiers: String? = nil
   ) {
     let inputText = AppleKeyboardConverter.cnvStringApple2ABC(inputText ?? "")
     let inputTextIgnoringModifiers = AppleKeyboardConverter.cnvStringApple2ABC(
@@ -147,7 +147,7 @@ struct InputSignal: CustomStringConvertible {
     self.inputTextIgnoringModifiers = inputTextIgnoringModifiers
     self.flags = flags
     isFlagChanged = false
-    useVerticalMode = isVerticalMode
+    isTypingVertical = isVerticalTyping
     self.keyCode = keyCode
     self.charCode = AppleKeyboardConverter.cnvApple2ABC(charCode)
     emacsKey = EmacsKeyHelper.detect(
@@ -157,14 +157,14 @@ struct InputSignal: CustomStringConvertible {
     defineArrowKeys()
   }
 
-  public init(event: NSEvent, isVerticalMode: Bool) {
+  public init(event: NSEvent, isVerticalTyping: Bool) {
     inputText = AppleKeyboardConverter.cnvStringApple2ABC(event.characters ?? "")
     inputTextIgnoringModifiers = AppleKeyboardConverter.cnvStringApple2ABC(
       event.charactersIgnoringModifiers ?? "")
     keyCode = event.keyCode
     flags = event.modifierFlags
     isFlagChanged = (event.type == .flagsChanged) ? true : false
-    useVerticalMode = isVerticalMode
+    isTypingVertical = isVerticalTyping
     let charCode: UInt16 = {
       // 這裡不用「count > 0」，因為該整數變數只要「!isEmpty」那就必定滿足這個條件。
       guard let inputText = event.characters, !inputText.isEmpty else {
@@ -182,16 +182,16 @@ struct InputSignal: CustomStringConvertible {
   }
 
   mutating func defineArrowKeys() {
-    cursorForwardKey = useVerticalMode ? .kDownArrow : .kRightArrow
-    cursorBackwardKey = useVerticalMode ? .kUpArrow : .kLeftArrow
-    extraChooseCandidateKey = useVerticalMode ? .kLeftArrow : .kDownArrow
-    extraChooseCandidateKeyReverse = useVerticalMode ? .kRightArrow : .kUpArrow
-    absorbedArrowKey = useVerticalMode ? .kRightArrow : .kUpArrow
-    verticalModeOnlyChooseCandidateKey = useVerticalMode ? absorbedArrowKey : .kNone
+    cursorForwardKey = isTypingVertical ? .kDownArrow : .kRightArrow
+    cursorBackwardKey = isTypingVertical ? .kUpArrow : .kLeftArrow
+    extraChooseCandidateKey = isTypingVertical ? .kLeftArrow : .kDownArrow
+    extraChooseCandidateKeyReverse = isTypingVertical ? .kRightArrow : .kUpArrow
+    absorbedArrowKey = isTypingVertical ? .kRightArrow : .kUpArrow
+    verticalTypingOnlyChooseCandidateKey = isTypingVertical ? absorbedArrowKey : .kNone
   }
 
   var description: String {
-    "<inputText:\(String(describing: inputText)), inputTextIgnoringModifiers:\(String(describing: inputTextIgnoringModifiers)) charCode:\(charCode), keyCode:\(keyCode), flags:\(flags), cursorForwardKey:\(cursorForwardKey), cursorBackwardKey:\(cursorBackwardKey), extraChooseCandidateKey:\(extraChooseCandidateKey), extraChooseCandidateKeyReverse:\(extraChooseCandidateKeyReverse), absorbedArrowKey:\(absorbedArrowKey),  verticalModeOnlyChooseCandidateKey:\(verticalModeOnlyChooseCandidateKey), emacsKey:\(emacsKey), useVerticalMode:\(useVerticalMode)>"
+    "<inputText:\(String(describing: inputText)), inputTextIgnoringModifiers:\(String(describing: inputTextIgnoringModifiers)) charCode:\(charCode), keyCode:\(keyCode), flags:\(flags), cursorForwardKey:\(cursorForwardKey), cursorBackwardKey:\(cursorBackwardKey), extraChooseCandidateKey:\(extraChooseCandidateKey), extraChooseCandidateKeyReverse:\(extraChooseCandidateKeyReverse), absorbedArrowKey:\(absorbedArrowKey),  verticalTypingOnlyChooseCandidateKey:\(verticalTypingOnlyChooseCandidateKey), emacsKey:\(emacsKey), isTypingVertical:\(isTypingVertical)>"
   }
 
   // 除了 ANSI charCode 以外，其餘一律過濾掉，免得純 Swift 版 KeyHandler 被餵屎。
@@ -334,8 +334,8 @@ struct InputSignal: CustomStringConvertible {
     KeyCode(rawValue: keyCode) == extraChooseCandidateKeyReverse
   }
 
-  var isVerticalModeOnlyChooseCandidateKey: Bool {
-    KeyCode(rawValue: keyCode) == verticalModeOnlyChooseCandidateKey
+  var isverticalTypingOnlyChooseCandidateKey: Bool {
+    KeyCode(rawValue: keyCode) == verticalTypingOnlyChooseCandidateKey
   }
 
   var isUpperCaseASCIILetterKey: Bool {
diff --git a/Source/Modules/ControllerModules/InputState.swift b/Source/Modules/ControllerModules/InputState.swift
index afdc0a46..65286924 100644
--- a/Source/Modules/ControllerModules/InputState.swift
+++ b/Source/Modules/ControllerModules/InputState.swift
@@ -317,11 +317,11 @@ class InputState {
   /// Represents that the user is choosing in a candidates list.
   class ChoosingCandidate: NotEmpty {
     private(set) var candidates: [String]
-    private(set) var useVerticalMode: Bool
+    private(set) var isTypingVertical: Bool
 
-    init(composingBuffer: String, cursorIndex: Int, candidates: [String], useVerticalMode: Bool) {
+    init(composingBuffer: String, cursorIndex: Int, candidates: [String], isTypingVertical: Bool) {
       self.candidates = candidates
-      self.useVerticalMode = useVerticalMode
+      self.isTypingVertical = isTypingVertical
       super.init(composingBuffer: composingBuffer, cursorIndex: cursorIndex)
     }
 
@@ -337,7 +337,7 @@ class InputState {
     }
 
     override var description: String {
-      "<InputState.ChoosingCandidate, candidates:\(candidates), useVerticalMode:\(useVerticalMode),  composingBuffer:\(composingBuffer), cursorIndex:\(cursorIndex)>"
+      "<InputState.ChoosingCandidate, candidates:\(candidates), isTypingVertical:\(isTypingVertical),  composingBuffer:\(composingBuffer), cursorIndex:\(cursorIndex)>"
     }
   }
 
@@ -347,27 +347,27 @@ class InputState {
   /// in the associated phrases mode.
   class AssociatedPhrases: InputState {
     private(set) var candidates: [String] = []
-    private(set) var useVerticalMode: Bool = false
-    init(candidates: [String], useVerticalMode: Bool) {
+    private(set) var isTypingVertical: Bool = false
+    init(candidates: [String], isTypingVertical: Bool) {
       self.candidates = candidates
-      self.useVerticalMode = useVerticalMode
+      self.isTypingVertical = isTypingVertical
       super.init()
     }
 
     var description: String {
-      "<InputState.AssociatedPhrases, candidates:\(candidates), useVerticalMode:\(useVerticalMode)>"
+      "<InputState.AssociatedPhrases, candidates:\(candidates), isTypingVertical:\(isTypingVertical)>"
     }
   }
 
   class SymbolTable: ChoosingCandidate {
     var node: SymbolNode
 
-    init(node: SymbolNode, useVerticalMode: Bool) {
+    init(node: SymbolNode, isTypingVertical: Bool) {
       self.node = node
       let candidates = node.children?.map(\.title) ?? [String]()
       super.init(
         composingBuffer: "", cursorIndex: 0, candidates: candidates,
-        useVerticalMode: useVerticalMode
+        isTypingVertical: isTypingVertical
       )
     }
 
@@ -388,7 +388,7 @@ class InputState {
     }
 
     override var description: String {
-      "<InputState.SymbolTable, candidates:\(candidates), useVerticalMode:\(useVerticalMode),  composingBuffer:\(composingBuffer), cursorIndex:\(cursorIndex)>"
+      "<InputState.SymbolTable, candidates:\(candidates), isTypingVertical:\(isTypingVertical),  composingBuffer:\(composingBuffer), cursorIndex:\(cursorIndex)>"
     }
   }
 }
diff --git a/Source/Modules/ControllerModules/KeyHandler_HandleInput.swift b/Source/Modules/ControllerModules/KeyHandler_HandleInput.swift
index acb9633f..5e51dad9 100644
--- a/Source/Modules/ControllerModules/KeyHandler_HandleInput.swift
+++ b/Source/Modules/ControllerModules/KeyHandler_HandleInput.swift
@@ -200,7 +200,7 @@ extension KeyHandler {
       if mgrPrefs.useSCPCTypingMode {
         let choosingCandidates: InputState.ChoosingCandidate = buildCandidate(
           state: inputting,
-          useVerticalMode: input.useVerticalMode
+          isTypingVertical: input.isTypingVertical
         )
         if choosingCandidates.candidates.count == 1 {
           clear()
@@ -213,7 +213,7 @@ extension KeyHandler {
             if let associatedPhrases =
               buildAssociatePhraseState(
                 withKey: text,
-                useVerticalMode: input.useVerticalMode
+                isTypingVertical: input.isTypingVertical
               ), !associatedPhrases.candidates.isEmpty
             {
               stateCallback(associatedPhrases)
@@ -243,7 +243,7 @@ extension KeyHandler {
     if let currentState = state as? InputState.NotEmpty, _composer.isEmpty,
       input.isExtraChooseCandidateKey || input.isExtraChooseCandidateKeyReverse || input.isSpace
         || input.isPageDown || input.isPageUp || (input.isTab && mgrPrefs.specifyShiftTabKeyBehavior)
-        || (input.useVerticalMode && (input.isVerticalModeOnlyChooseCandidateKey))
+        || (input.isTypingVertical && (input.isverticalTypingOnlyChooseCandidateKey))
     {
       if input.isSpace {
         // If the Space key is NOT set to be a selection key
@@ -266,7 +266,7 @@ extension KeyHandler {
           return true
         }
       }
-      stateCallback(buildCandidate(state: currentState, useVerticalMode: input.useVerticalMode))
+      stateCallback(buildCandidate(state: currentState, isTypingVertical: input.isTypingVertical))
       return true
     }
 
@@ -368,7 +368,7 @@ extension KeyHandler {
             let inputting = buildInputtingState
             inputting.poppedText = poppedText
             stateCallback(inputting)
-            stateCallback(buildCandidate(state: inputting, useVerticalMode: input.useVerticalMode))
+            stateCallback(buildCandidate(state: inputting, isTypingVertical: input.isTypingVertical))
           } else {  // If there is still unfinished bpmf reading, ignore the punctuation
             IME.prtDebugIntel("17446655")
             errorCallback()
@@ -380,7 +380,7 @@ extension KeyHandler {
         // 於是這裡用「模擬一次 Enter 鍵的操作」使其代為執行這個 commit buffer 的動作。
         // 這裡不需要該函數所傳回的 bool 結果，所以用「_ =」解消掉。
         _ = handleEnter(state: state, stateCallback: stateCallback, errorCallback: errorCallback)
-        stateCallback(InputState.SymbolTable(node: SymbolNode.root, useVerticalMode: input.useVerticalMode))
+        stateCallback(InputState.SymbolTable(node: SymbolNode.root, isTypingVertical: input.isTypingVertical))
         return true
       }
     }
@@ -411,7 +411,7 @@ extension KeyHandler {
     if handlePunctuation(
       customPunctuation,
       state: state,
-      usingVerticalMode: input.useVerticalMode,
+      usingVerticalTyping: input.isTypingVertical,
       stateCallback: stateCallback,
       errorCallback: errorCallback
     ) {
@@ -425,7 +425,7 @@ extension KeyHandler {
     if handlePunctuation(
       punctuation,
       state: state,
-      usingVerticalMode: input.useVerticalMode,
+      usingVerticalTyping: input.isTypingVertical,
       stateCallback: stateCallback,
       errorCallback: errorCallback
     ) {
@@ -438,7 +438,7 @@ extension KeyHandler {
       if handlePunctuation(
         letter,
         state: state,
-        usingVerticalMode: input.useVerticalMode,
+        usingVerticalTyping: input.isTypingVertical,
         stateCallback: stateCallback,
         errorCallback: errorCallback
       ) {
diff --git a/Source/Modules/ControllerModules/KeyHandler_States.swift b/Source/Modules/ControllerModules/KeyHandler_States.swift
index 2c4ea14a..6c516dbc 100644
--- a/Source/Modules/ControllerModules/KeyHandler_States.swift
+++ b/Source/Modules/ControllerModules/KeyHandler_States.swift
@@ -147,13 +147,13 @@ extension KeyHandler {
 
   func buildCandidate(
     state currentState: InputState.NotEmpty,
-    useVerticalMode: Bool = false
+    isTypingVertical: Bool = false
   ) -> InputState.ChoosingCandidate {
     InputState.ChoosingCandidate(
       composingBuffer: currentState.composingBuffer,
       cursorIndex: currentState.cursorIndex,
       candidates: candidatesArray,
-      useVerticalMode: useVerticalMode
+      isTypingVertical: isTypingVertical
     )
   }
 
@@ -168,11 +168,11 @@ extension KeyHandler {
   // 是否為空：如果陣列為空的話，直接回呼一個空狀態。
   func buildAssociatePhraseState(
     withKey key: String!,
-    useVerticalMode: Bool
+    isTypingVertical: Bool
   ) -> InputState.AssociatedPhrases! {
     // 上一行必須要用驚嘆號，否則 Xcode 會誤導你砍掉某些實際上必需的語句。
     InputState.AssociatedPhrases(
-      candidates: buildAssociatePhraseArray(withKey: key), useVerticalMode: useVerticalMode
+      candidates: buildAssociatePhraseArray(withKey: key), isTypingVertical: isTypingVertical
     )
   }
 
@@ -251,7 +251,7 @@ extension KeyHandler {
   func handlePunctuation(
     _ customPunctuation: String,
     state: InputState,
-    usingVerticalMode useVerticalMode: Bool,
+    usingVerticalTyping isTypingVertical: Bool,
     stateCallback: @escaping (InputState) -> Void,
     errorCallback: @escaping () -> Void
   ) -> Bool {
@@ -269,7 +269,7 @@ extension KeyHandler {
       if mgrPrefs.useSCPCTypingMode, _composer.isEmpty {
         let candidateState = buildCandidate(
           state: inputting,
-          useVerticalMode: useVerticalMode
+          isTypingVertical: isTypingVertical
         )
         if candidateState.candidates.count == 1 {
           clear()
diff --git a/Source/Modules/IMEModules/ctlInputMethod.swift b/Source/Modules/IMEModules/ctlInputMethod.swift
index edd0a42e..d84cf7c2 100644
--- a/Source/Modules/IMEModules/ctlInputMethod.swift
+++ b/Source/Modules/IMEModules/ctlInputMethod.swift
@@ -168,7 +168,7 @@ class ctlInputMethod: IMKInputController {
       forCharacterIndex: 0, lineHeightRectangle: &textFrame
     )
 
-    let useVerticalMode =
+    let isTypingVertical =
       (attributes?["IMKTextOrientation"] as? NSNumber)?.intValue == 0 || false
 
     if client.bundleIdentifier()
@@ -179,7 +179,7 @@ class ctlInputMethod: IMKInputController {
       IME.areWeUsingOurOwnPhraseEditor = false
     }
 
-    let input = InputSignal(event: event, isVerticalMode: useVerticalMode)
+    let input = InputSignal(event: event, isVerticalTyping: isTypingVertical)
 
     // 無法列印的訊號輸入，一概不作處理。
     // 這個過程不能放在 KeyHandler 內，否則不會起作用。
@@ -457,17 +457,17 @@ extension ctlInputMethod {
 
 extension ctlInputMethod {
   private func show(candidateWindowWith state: InputState, client: Any!) {
-    var useVerticalMode: Bool {
-      var useVerticalMode = false
+    var isTypingVertical: Bool {
+      var isTypingVertical = false
       var candidates: [String] = []
       if let state = state as? InputState.ChoosingCandidate {
-        useVerticalMode = state.useVerticalMode
+        isTypingVertical = state.isTypingVertical
         candidates = state.candidates
       } else if let state = state as? InputState.AssociatedPhrases {
-        useVerticalMode = state.useVerticalMode
+        isTypingVertical = state.isTypingVertical
         candidates = state.candidates
       }
-      if useVerticalMode { return true }
+      if isTypingVertical { return true }
       candidates.sort {
         $0.count > $1.count
       }
@@ -481,7 +481,7 @@ extension ctlInputMethod {
 
     ctlCandidateCurrent.delegate = nil
 
-    if useVerticalMode {
+    if isTypingVertical {
       ctlCandidateCurrent.currentLayout = .vertical
     } else if mgrPrefs.useHorizontalCandidateList {
       ctlCandidateCurrent.currentLayout = .horizontal
@@ -552,7 +552,7 @@ extension ctlInputMethod {
       cursor -= 1
     }
 
-    if useVerticalMode {
+    if isTypingVertical {
       ctlCandidateCurrent.set(
         windowTopLeftPoint: NSPoint(
           x: lineHeightRect.origin.x + lineHeightRect.size.width + 4.0, y: lineHeightRect.origin.y - 4.0
@@ -662,7 +662,7 @@ extension ctlInputMethod: ctlCandidateDelegate {
     {
       if let children = node.children, !children.isEmpty {
         handle(
-          state: .SymbolTable(node: node, useVerticalMode: state.useVerticalMode),
+          state: .SymbolTable(node: node, isTypingVertical: state.isTypingVertical),
           client: currentClient
         )
       } else {
@@ -684,7 +684,7 @@ extension ctlInputMethod: ctlCandidateDelegate {
         handle(state: .Committing(poppedText: composingBuffer), client: client)
         if mgrPrefs.associatedPhrasesEnabled,
           let associatePhrases = keyHandler.buildAssociatePhraseState(
-            withKey: composingBuffer, useVerticalMode: state.useVerticalMode
+            withKey: composingBuffer, isTypingVertical: state.isTypingVertical
           ), !associatePhrases.candidates.isEmpty
         {
           handle(state: associatePhrases, client: client)
@@ -702,7 +702,7 @@ extension ctlInputMethod: ctlCandidateDelegate {
       handle(state: .Committing(poppedText: selectedValue), client: currentClient)
       if mgrPrefs.associatedPhrasesEnabled,
         let associatePhrases = keyHandler.buildAssociatePhraseState(
-          withKey: selectedValue, useVerticalMode: state.useVerticalMode
+          withKey: selectedValue, isTypingVertical: state.isTypingVertical
         ), !associatePhrases.candidates.isEmpty
       {
         handle(state: associatePhrases, client: client)