<html><head><meta name="color-scheme" content="light dark"></head><body><pre style="word-wrap: break-word; white-space: pre-wrap;">\subsection{Identification (0x00)}

As an example of CATS' extreme flexibility, even the packet's identification exists in a whisker. When using CATS as intended, this whisker will likely always be included. There are some situations where it may not be, however. For example, to save data it could be omitted in some packets, as long as it is included often enough for legal station identification. It could also be omitted if CATS is being used outside of amateur frequencies. \textbf{A valid CATS packet contains a maximum of one identification whisker.}

The callsign is an arbitrary string of UTF-8 up to 252 bytes long. In most cases, it should be much shorter. One remaining byte at the end is for the SSID. This allows up to 255 different stations to share a single callsign.

The identification whisker also has 2 bytes which specify an icon. CATS icons are loosely equivalent to APRS symbols. Two bytes allows a maximum of 65536 different icons. For now, only a handful are defined, though this list will evolve with the standard. All icon IDs are valid, even those that don't currently correspond with an icon. This property is essential to allow the icon list to grow while ensuring backwards-compatibility with older nodes.

\subsubsection{Structure}

\begin{tabularx}{\textwidth}{|l|l|l|X|}
  \hline
  \textbf{Byte offset} &amp; \textbf{Length} &amp; \textbf{Value} &amp; \textbf{Description} \\
  \hline
  0 &amp; 1 &amp; 0x00 &amp; Whisker type \\
  \hline
  1 &amp; 1 &amp; $N$ &amp; Whisker length in bytes \\
  \hline
  2 &amp; 2 &amp; &amp; Icon ID \\
  \hline
  4 &amp; $N - 3$ &amp; &amp; Callsign data \\
  \hline
  $N + 1$ &amp; 1 &amp; &amp; SSID \\
  \hline
\end{tabularx}

\subsubsection{Icon Table}

\begin{tabular}{|l|l|}
  \hline
  \textbf{Icon ID} &amp; \textbf{Icon Name} \\
  \hline
  0 &amp; [No Icon] \\
  \hline
  1 &amp; Cat \\
  \hline
  2 &amp; Car \\
  \hline
  3 &amp; House \\
  \hline
  4 &amp; Office building \\
  \hline
  5 &amp; Truck \\
  \hline
  6 &amp; Van \\
  \hline
  7 &amp; Red Square \\
  \hline
  8 &amp; Orange Square \\
  \hline
  9 &amp; Yellow Square \\
  \hline
  10 &amp; Green Square \\
  \hline
  11 &amp; Blue Square \\
  \hline
  12 &amp; Purple Square \\
  \hline
  13 &amp; Balloon \\
  \hline
  14 &amp; Airplane \\
  \hline
  15 &amp; Helicopter \\
  \hline
  16 &amp; Bus \\
  \hline
  17 &amp; Train \\
  \hline
  18 &amp; Person \\
  \hline
  19 &amp; Warning \\
  \hline
  20 &amp; Error \\
  \hline
  21 &amp; Satellite \\
  \hline
  22 &amp; Computer \\
  \hline
  23 &amp; Bicycle \\
  \hline
  24 &amp; Motorcycle \\
  \hline
\end{tabular}
</pre></body></html>