diff --git a/src/args/flags.rs b/src/args/flags.rs
index f7851b8..c85e1bb 100644
--- a/src/args/flags.rs
+++ b/src/args/flags.rs
@@ -28,21 +28,97 @@ pub enum Kind<'a>
     /// A single `--`.
     ///
     /// # Note
-    /// Shorthand for `Long(&[], false)`
+    /// Shorthand for `Long(&[], _)`
     Terminator,
     /// A single `-`.
     ///
     /// # Note
-    /// Shorthand for `Short(&[], false)`
+    /// Shorthand for `Short(&[], _)`
     TerminatorShort,
     /// An exact match with no prefix and flag for case-sensitivity.
     Exact(&'a str, bool),
-    /// Match everything,
+    /// Match everything.
     Any,
 }
 
 impl<'b> Kind<'b>
 {
+    /// Check if string `value` matches this `Kind`.
+    ///
+    /// Returns the matched part.
+    /// # Note
+    /// In this case of `Short` (or `Abrev` short match), return the rest of the argument string including the matched character
+    ///
+    /// # Short case-sensitivity
+    /// Single character matching case sensitivity can produce unexpected results if the lowercase transform of that character yields multiple characters. They are all checked for match.
+    pub fn is_match<'a, 'c>(&'a self, value: &'b str) -> Option<&'a str>
+    where 'c: 'a,
+    'a: 'b
+    {
+	match self {
+	    Self::Long(&[], _) |
+	    Self::Abrev(&[], &[], _, _) |
+	    Self::Terminator if value == "--" => Some("--"),
+	    
+ 	    Self::Short(&[], _) |
+	    Self::TerminatorShort if value == "-" => Some("-"),
+	    
+	    Self::Abrev(any, _, true, _) |
+	    Self::Long(any, true) if value.starts_with("--") => {
+		let value = &value[2..];
+		
+		for &which in any.iter() {
+		    if which == value {
+			return Some(which);
+		    }
+		}
+		None
+	    },
+	    Self::Abrev(any, _, false, _) |
+	    Self::Long(any, false) if value.starts_with("--") => {
+		let value = value[2..].to_lowercase();
+		
+		for (orig, which) in any.iter().map(|x| (x, x.to_lowercase())) {
+		    if which == value {
+			return Some(orig);
+		    }
+		}
+		None
+	    },
+
+	    Self::Abrev(_, any, _, true) |
+	    Self::Short(any, true) if value.starts_with("-") => {
+		let mut value = value[1..].chars();
+		let iter = &mut value;
+		for can_be in iter {
+		    if any.contains(&(can_be,)) {
+			return Some(value.as_str());
+		    }
+		}
+		None
+	    },
+	    
+	    //Self::Abrev(_, any, _, false) |
+	    Self::Short(any, false) if value.starts_with("-") => {
+		let mut value = value[1..].chars();
+		let iter = &mut value;
+		let any: Vec<_> = any.iter().flat_map(|(chr,)| chr.to_lowercase()).collect();
+		for can_be in iter.flat_map(|x| x.to_lowercase()) {
+		    if any.contains(&can_be) {
+			return Some(value.as_str());
+		    }
+		}
+		None
+	    },
+	    
+	    Self::Exact(exact, false) if value.to_lowercase() == exact.to_lowercase() => Some(value),
+	    Self::Exact(exact, true) if &value == exact => Some(value),
+	    
+	    Self::Any => Some(value),
+	    _ => None,
+	}
+    }
+    /// Create a reference to this `Kind` with a lower lifetime.
     pub fn as_ref<'a>(&'a self) -> Kind<'a>
     {
 	match &self {
@@ -55,8 +131,18 @@ impl<'b> Kind<'b>
 	    Self::Any => Kind::Any,
 	}
     }
-}
 
+    /// Split `Kind::Abrev` into short and long
+    pub fn split_abrev(&self) -> Result<(Kind<'_>, Kind<'_>), &Self>
+    {
+	match self {
+	    Self::Abrev(long, short, lcase, scase) => {
+		Ok((Kind::Long(long,*lcase), Kind::Short(short, *scase)))
+	    },
+	    e => Err(e)
+	}
+    }
+}
 
 /// Helper for `Cow` variants
 macro_rules! cow
@@ -274,15 +360,18 @@ impl<U> ArgState<U>
 		if *single {
 		    *chk = false;
 		}
-		//TODO: Check Kind  matches `arg`, check `value` matches `input` and get the values.
-		output.push(callback(&mut StateHandle{
-		    state: &mut self.user,
-		    args: &mut input,
-		    chk,
-		    idx: i,
-		    held: Either::None, //TODO: This will be for either one `=<value>` or many `<values...>` from args as according to `value`.
-		}, i, &arg[..])
-			    .map_err(|err| Error{flag: kind.clone(), from: err, desc: Some(desc.clone().into_owned()), arg: (i, arg.clone())})?);
+		//TODO: When value is `Equals`, split at `=` and pass only the first part to `is_match`.
+		if let Some(kind_match) = kind.is_match(&arg[..]) {
+		    //TODO: Check `value` matches `input` or `kind_match`
+		    output.push(callback(&mut StateHandle{
+			state: &mut self.user,
+			args: &mut input,
+			chk,
+			idx: i,
+			held: Either::None, //TODO: This will be for either one `=<value>` or many `<values...>` from args as according to `value`.
+		    }, i, kind_match)
+				.map_err(|err| Error{flag: kind.clone(), from: err, desc: Some(desc.clone().into_owned()), arg: (i, arg.clone())})?);
+		}
 	    }
 	    i+=1;
 	}