Excel: Creating Unique Indentifiers
<p>I'm looking to create a unique identifier column for a table in excel based on a few criteria. I've attached a picture with an example table below for reference.</p>

<p>Example excel table</p>

<p><a href="https://i.stack.imgur.com/1PFio.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/1PFio.png" alt="enter image description here"></a></p>

<p>What I'm looking to create is something like the third column "Unique ID", however, I'm having a hard time given the criteria I need to meet:</p>

<ul>
<li><ol>
<li>The ID needs to begin with the first letter of the "Category"</li>
</ol></li>
<li><ol start="2">
<li>Each categories ID needs to begin at 1 when it's first introduced but continue where it left off when its re-introduced.</li>
</ol></li>
<li><ol start="3">
<li>If a category has the same "Type", the "Unique ID" needs to create some kind of addition subset id such as ".1", "a", etc.</li>
</ol></li>
</ul>

<p>If anyone has any suggestions I'd really appreciate it.</p>

<p>Thanks in advance!</p>