Just adding some comments.

I was shifting before masking because I had been using a larger mask,
u16. Now it masks then shifts because I had changed it to being a u8
mask for each section.

LICENSE.md

@@ -1,69 +1,174 @@
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+### 7. Disclaimer of Warranty.
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+provides the Work (and each Contributor provides its Contributions) on
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+### 8. Limitation of Liability.
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+In no event and under no legal theory, whether in tort (including
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+### 9. Accepting Warranty or Additional Liability.
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README.md

@@ -49,3 +49,19 @@ Library avoids panics where possible and returns Result<T, &str> for error handl
 
 ## References
 [SPP]: https://ccsds.org/wp-content/uploads/gravity_forms/5-448e85c647331d9cbaf66c096458bdd5/2025/01//133x0b2e2.pdf "CCSDS Space Packet Protocol PDF"
+
+
+---
+
+## Copyright & License
+
+Copyright 2025 CyberMages LLC
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this library except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS

src/bits.rs

@@ -1,40 +1,104 @@
+/// Trait for types that can be parsed from a byte slice.
+///
+/// Implementors define how a type is reconstructed from raw bytes, returning
+/// the number of bytes consumed and the resulting value.
 pub trait FromBytes: Sized
 {
    type Error;
 
+   /// Parse `Self` from a slice of bytes.
+   ///
+   /// # Parameters
+   /// - `bytes`: Input slice containing raw data.
+   ///
+   /// # Returns
+   /// A [`Parsed`] struct with the parsed value and bytes consumed, or an error.
+   ///
+   /// # Example
+   /// ```
+   /// ```
    fn from_bytes(bytes: &[u8]) -> Result<Parsed<Self>, Self::Error>;
 }
 
+/// Trait for types that can be serialized into a byte slice.
+///
+/// Implementors define how a type converts itself into a buffer of bytes.
 pub trait IntoBytes
 {
    type Error;
 
+   /// Serialize `Self` into the provided byte buffer.
+   ///
+   /// # Parameters
+   /// - `buffer`: Mutable slice where the serialized data will be written.
+   ///
+   /// # Returns
+   /// The number of bytes written, or an error.
    fn into_bytes(self, buffer: &mut [u8]) -> Result<usize, Self::Error>;
 }
 
+/// Trait for types that can be parsed from a bitfield.
+///
+/// This is useful for partial-byte fields or packed data structures.
 pub trait FromBits: Sized
 {
    type Error;
 
+   /// Parse `Self` from a byte slice using a bitmask.
+   ///
+   /// # Parameters
+   /// - `bytes`: Input slice containing raw data.
+   /// - `mask`: Bitmask indicating which bits are relevant for parsing.
+   ///
+   /// # Returns
+   /// The parsed value or an error.
    fn from_bits(bytes: &[u8], mask: &[u8]) -> Result<Self, Self::Error>;
 }
 
+/// Trait for types that can be serialized into a bitfield.
+///
+/// Allows writing values into selected bits of a buffer.
 pub trait IntoBits
 {
    type Error;
 
+   /// Serialize `Self` into a byte slice using a bitmask.
+   ///
+   /// # Parameters
+   /// - `bytes`: Mutable slice where the bits will be written.
+   /// - `mask`: Bitmask indicating which bits to modify.
+   ///
+   /// # Returns
+   /// `Ok(())` on success, or an error.
    fn into_bits(self, bytes: &mut [u8], mask: &[u8]) -> Result<(), Self::Error>;
 }
 
 
+/// Represents a parsed value and the number of bytes consumed during parsing.
+///
+/// This is returned by [`FromBytes::from_bytes`] to indicate how many bytes
+/// were read and the resulting value.
 pub struct Parsed<T>
 {
+   /// The number of bytes read from the input buffer.
    pub bytes_read: usize,
+
+   /// The parsed value.
    pub data: T
 }
 
+
+
 impl<T> Parsed<T>
 {
+   /// Construct a new `Parsed` instance.
+   ///
+   /// # Parameters
+   /// - `bytes_read`: Number of bytes consumed.
+   /// - `data`: The parsed value.
+   ///
+   /// # Returns
+   /// A `Parsed` struct containing the data and bytes read.
    pub fn new(bytes_read: usize, data: T) -> Self
    {
       Parsed

src/header.rs

@@ -1,3 +1,5 @@
+//! # Header
+//! The 
 use crate::bits::*;
 
 
@@ -41,8 +43,8 @@ impl FromBytes for ApId
    {
       if bytes.len() < 2usize { return Err("ERROR"); }
 
-      let id: u16 = (((bytes[0] as u16) << 8) & ApId::MASK_ARR[0]) |
-                    ((bytes[1] as u16) & ApId::MASK_ARR[1]);
+      let id: u16 = (((bytes[0] & ApId::MASK_ARR[0]) as u16) << 8) |
+                    (((bytes[1] & ApId::MASK_ARR[1]) as u16));
 
       Ok(Parsed::new(2usize, id.into()))
    }
@@ -56,7 +58,7 @@ impl IntoBytes for ApId
    {
       if buffer.len() < 2usize { return Err("Error"); }
 
-      let id: u16 = self.from();
+      let id: u16 = self.value;
 
       buffer[0] = ((id >> 8) as u8) & ApId::MASK_ARR[0];
       buffer[1] = (id as u8) & ApId::MASK_ARR[0];
@@ -88,7 +90,7 @@ impl IntoBits for ApId
    {
       if bytes.len() < 2usize || mask.len() < 2usize { return Err("Error"); }
 
-      let id: u16 = self.from();
+      let id: u16 = self.value;
 
       bytes[0] = ((id >> 8) as u8) & mask[0];
       bytes[1] = (id as u8) & mask[1];
@@ -189,6 +191,7 @@ pub enum PacketType
 
 const TYPE_TELEMETRY: u8 = 0b00000000;
 const TYPE_TELECOMMAND: u8 = 0b00010000;
+
 impl PacketType
 {
    pub const MASK_U8: u8 = 0b00010000;

src/lib.rs

@@ -1,4 +1,17 @@
-//! CCSDS Space Packet Protocol
+//! # CCSDS Space Packet Protocol
+//! This library implements the
+//! [CCSDS Space Packet Protocol (CCSDS 133.0-B-2)][SPP],
+//! providing a standardized means of encapsulating and routing telemetry and
+//! telecommand data in space communication systems.
+//!
+//! The Space Packet Protocol defines a uniform structure for data exchange
+//! between spacecraft subsystems and ground stations. Each packet contains a
+//! primary header, an optional secondary header, and an application data field.
+//!
+//! ## References
+//! - [CCSDS 133.0-B-2, *Space Packet Protocol*, Issue 2, September 2012][SPP]
+//!
+//! [SPP]: https://ccsds.org/wp-content/uploads/gravity_forms/5-448e85c647331d9cbaf66c096458bdd5/2025/01//133x0b2e2.pdf "CCSDS Space Packet Protocol PDF"
 
 mod project;