diff --git a/sub_crates/text_encoding/src/latin1.rs b/sub_crates/text_encoding/src/latin1.rs
index d3c8a0d..71df924 100644
--- a/sub_crates/text_encoding/src/latin1.rs
+++ b/sub_crates/text_encoding/src/latin1.rs
@@ -8,7 +8,7 @@
 use std;
 use {DecodeResult, EncodeError, EncodeResult};
 
-pub fn encode_from_utf8(input: &str, output: &mut [u8]) -> EncodeResult {
+pub fn encode_from_utf8<'a>(input: &str, output: &'a mut [u8]) -> EncodeResult<'a> {
     // Do the encode.
     let mut input_i = 0;
     let mut output_i = 0;
@@ -19,8 +19,8 @@ pub fn encode_from_utf8(input: &str, output: &mut [u8]) -> EncodeResult {
         if c as u32 > 255 {
             return Err(EncodeError {
                 character: c,
-                byte_offset: offset,
-                bytes_written: output_i,
+                error_range: (offset, offset + c.len_utf8()),
+                output_bytes_written: output_i,
             });
         }
         output[output_i] = c as u8;
@@ -38,7 +38,7 @@ pub fn encode_from_utf8(input: &str, output: &mut [u8]) -> EncodeResult {
         }
     }
 
-    Ok((input_i, output_i))
+    Ok((input_i, &output[..output_i]))
 }
 
 pub fn decode_to_utf8<'a>(input: &[u8], output: &'a mut [u8]) -> DecodeResult<'a> {
diff --git a/sub_crates/text_encoding/src/lib.rs b/sub_crates/text_encoding/src/lib.rs
index da17fe9..d4d0628 100644
--- a/sub_crates/text_encoding/src/lib.rs
+++ b/sub_crates/text_encoding/src/lib.rs
@@ -7,7 +7,11 @@ mod utf16_le;
 mod utf8;
 
 /// Encodes text from utf8 to a destination encoding.
-pub fn encode_from_utf8(output_encoding: Encoding, input: &str, output: &mut [u8]) -> EncodeResult {
+pub fn encode_from_utf8<'a>(
+    output_encoding: Encoding,
+    input: &str,
+    output: &'a mut [u8],
+) -> EncodeResult<'a> {
     match output_encoding {
         Encoding::Utf8 => utf8::encode_from_utf8(input, output),
         Encoding::Utf16BE => utf16_be::encode_from_utf8(input, output),
@@ -48,9 +52,9 @@ pub enum Encoding {
 
 /// Result type for encoding text from utf8 to a target encoding.
 ///
-/// The Ok() variant provides the number of bytes consumed and the
-/// number of bytes written, in that order.
-pub type EncodeResult = Result<(usize, usize), EncodeError>;
+/// The Ok() variant provides the number of bytes consumed and a reference
+/// to the valid encoded text data.
+pub type EncodeResult<'a> = Result<(usize, &'a [u8]), EncodeError>;
 
 /// Result type for decoding text from a target encoding to utf8.
 ///
@@ -64,17 +68,17 @@ pub type DecodeResult<'a> = Result<(usize, &'a str), DecodeError>;
 /// error is encountering a char that is not representable in the target
 /// encoding.
 ///
-/// The problematic character, the byte offset of that character
-/// in the input utf8, and the number of bytes already written to the output
-/// buffer is provided.
+/// The problematic character, the byte index range of that character in the
+/// input utf8, and the number of bytes already written to the output buffer
+/// are provided.
 ///
 /// It is guaranteed that all input leading up to the problem character has
 /// already been encoded and written to the output buffer.
 #[derive(Debug, Copy, Clone)]
 pub struct EncodeError {
     pub character: char,
-    pub byte_offset: usize,
-    pub bytes_written: usize,
+    pub error_range: (usize, usize),
+    pub output_bytes_written: usize,
 }
 
 /// Represents an error when decoding to utf8 from some other format.
@@ -84,14 +88,13 @@ pub struct EncodeError {
 /// input data that are invalid for the text encoding we're attempting
 /// to decode from.
 ///
-/// The byte offset of the invalid input data and in the number of bytes
-/// already written to the output buffer are.
-/// already been encoded and written to the output buffer.
+/// The byte index range of the invalid input data and the number of bytes
+/// already encoded and written to the output buffer are provided.
 ///
 /// It is guaranteed that all input leading up to the invalid data has
 /// already been encoded and written to the output buffer.
 #[derive(Debug, Copy, Clone)]
 pub struct DecodeError {
-    pub byte_offset: usize,
-    pub bytes_written: usize,
+    pub error_range: (usize, usize),
+    pub output_bytes_written: usize,
 }
diff --git a/sub_crates/text_encoding/src/utf16_be.rs b/sub_crates/text_encoding/src/utf16_be.rs
index 439beb6..152b55f 100644
--- a/sub_crates/text_encoding/src/utf16_be.rs
+++ b/sub_crates/text_encoding/src/utf16_be.rs
@@ -35,7 +35,7 @@ fn from_big_endian(n: [u8; 2]) -> u16 {
     x
 }
 
-pub fn encode_from_utf8(input: &str, output: &mut [u8]) -> EncodeResult {
+pub fn encode_from_utf8<'a>(input: &str, output: &'a mut [u8]) -> EncodeResult<'a> {
     // Do the encode.
     let mut input_i = 0;
     let mut output_i = 0;
@@ -78,7 +78,7 @@ pub fn encode_from_utf8(input: &str, output: &mut [u8]) -> EncodeResult {
         }
     }
 
-    Ok((input_i, output_i))
+    Ok((input_i, &output[..output_i]))
 }
 
 pub fn decode_to_utf8<'a>(input: &[u8], output: &'a mut [u8]) -> DecodeResult<'a> {
@@ -101,8 +101,8 @@ pub fn decode_to_utf8<'a>(input: &[u8], output: &'a mut [u8]) -> DecodeResult<'a
             } else if (code_1 & 0xFC00) == 0xDC00 {
                 // Error: orphaned second half of a surrogate pair.
                 return Err(DecodeError {
-                    byte_offset: input_i,
-                    bytes_written: output_i,
+                    error_range: (input_i, input_i + 2),
+                    output_bytes_written: output_i,
                 });
             } else {
                 // Two code units.
@@ -116,8 +116,8 @@ pub fn decode_to_utf8<'a>(input: &[u8], output: &'a mut [u8]) -> DecodeResult<'a
                 if !(code_2 & 0xFC00) == 0xDC00 {
                     // Error: second half is not valid surrogate.
                     return Err(DecodeError {
-                        byte_offset: input_i,
-                        bytes_written: output_i,
+                        error_range: (input_i, input_i + 2),
+                        output_bytes_written: output_i,
                     });
                 }
 
diff --git a/sub_crates/text_encoding/src/utf16_le.rs b/sub_crates/text_encoding/src/utf16_le.rs
index 9e235c3..f0860dd 100644
--- a/sub_crates/text_encoding/src/utf16_le.rs
+++ b/sub_crates/text_encoding/src/utf16_le.rs
@@ -35,7 +35,7 @@ fn from_little_endian(n: [u8; 2]) -> u16 {
     x
 }
 
-pub fn encode_from_utf8(input: &str, output: &mut [u8]) -> EncodeResult {
+pub fn encode_from_utf8<'a>(input: &str, output: &'a mut [u8]) -> EncodeResult<'a> {
     // Do the encode.
     let mut input_i = 0;
     let mut output_i = 0;
@@ -78,7 +78,7 @@ pub fn encode_from_utf8(input: &str, output: &mut [u8]) -> EncodeResult {
         }
     }
 
-    Ok((input_i, output_i))
+    Ok((input_i, &output[..output_i]))
 }
 
 pub fn decode_to_utf8<'a>(input: &[u8], output: &'a mut [u8]) -> DecodeResult<'a> {
@@ -101,8 +101,8 @@ pub fn decode_to_utf8<'a>(input: &[u8], output: &'a mut [u8]) -> DecodeResult<'a
             } else if (code_1 & 0xFC00) == 0xDC00 {
                 // Error: orphaned second half of a surrogate pair.
                 return Err(DecodeError {
-                    byte_offset: input_i,
-                    bytes_written: output_i,
+                    error_range: (input_i, input_i + 2),
+                    output_bytes_written: output_i,
                 });
             } else {
                 // Two code units.
@@ -116,8 +116,8 @@ pub fn decode_to_utf8<'a>(input: &[u8], output: &'a mut [u8]) -> DecodeResult<'a
                 if !(code_2 & 0xFC00) == 0xDC00 {
                     // Error: second half is not valid surrogate.
                     return Err(DecodeError {
-                        byte_offset: input_i,
-                        bytes_written: output_i,
+                        error_range: (input_i, input_i + 2),
+                        output_bytes_written: output_i,
                     });
                 }
 
diff --git a/sub_crates/text_encoding/src/utf8.rs b/sub_crates/text_encoding/src/utf8.rs
index 404edf8..830b03c 100644
--- a/sub_crates/text_encoding/src/utf8.rs
+++ b/sub_crates/text_encoding/src/utf8.rs
@@ -7,7 +7,7 @@ use std;
 use {DecodeError, DecodeResult, EncodeResult};
 
 // Encode from utf8
-pub fn encode_from_utf8(input: &str, output: &mut [u8]) -> EncodeResult {
+pub fn encode_from_utf8<'a>(input: &str, output: &'a mut [u8]) -> EncodeResult<'a> {
     let copy_len = {
         if output.len() >= input.len() {
             input.len()
@@ -22,7 +22,7 @@ pub fn encode_from_utf8(input: &str, output: &mut [u8]) -> EncodeResult {
 
     output[..copy_len].copy_from_slice(input[..copy_len].as_bytes());
 
-    Ok((copy_len, copy_len))
+    Ok((copy_len, &output[..copy_len]))
 }
 
 pub fn decode_to_utf8<'a>(input: &[u8], output: &'a mut [u8]) -> DecodeResult<'a> {
@@ -33,19 +33,19 @@ pub fn decode_to_utf8<'a>(input: &[u8], output: &'a mut [u8]) -> DecodeResult<'a
                 e.valid_up_to()
             } else {
                 return Err(DecodeError {
-                    byte_offset: 0,
-                    bytes_written: 0,
+                    error_range: (0, 1), // TODO: search for the next starting byte to get the range.
+                    output_bytes_written: 0,
                 });
             }
         }
     };
 
-    let (in_consumed, out_written) = encode_from_utf8(
+    let (in_consumed, out_slice) = encode_from_utf8(
         unsafe { std::str::from_utf8_unchecked(&input[..valid_up_to]) },
         output,
     ).unwrap();
 
     Ok((in_consumed, unsafe {
-        std::str::from_utf8_unchecked(&output[..out_written])
+        std::str::from_utf8_unchecked(out_slice)
     }))
 }