Why are inserted legislation section identifiers often preceded by a &quot;z&quot;?
<p>Many times, in UK legislation, the structure is of numbered sections, like 1., 2., 3...</p>
<p>Sometimes a subsequent act will insert sections that append lettered suffixes to the numbered section identifiers that precede their placement position within the act being amended, so that you might easily end up with sections 1, 1A, 2, 3, etc., which is also very sensibly understandable.</p>
<p>Other times, one finds added sections that add a Z before the A/B/C, etc. So you may get 1, 2, 2za, 2zb, 2zc, 3, etc. Obviously these are just section enumeration conventions, and could just as easily be entirely arbitrary subject to the whim and caprice of Parliament, but I assume that there is a discernible formula and pattern to them, and I wonder what it is. What is the significance or motivation for the convention of adding an additional 'Z' to inserted subsections?</p>
<p>As a corollary, what general procedural codes exist to guide (or bind) the parliamentary legislative draftspeople? Surely there must be style guides that they are bound to follow. What are these, and would they have the force of law?</p>

<p>They follow the rules within the <a href="https://www.gov.uk/government/publications/drafting-bills-for-parliament" rel="nofollow noreferrer">Office of the Parliamentary Counsel drafting guidance</a></p>
<blockquote>
<p><strong>6.4 NUMBERING OF INSERTED PROVISIONS</strong></p>
<p><strong>At the beginning of a series</strong></p>
<p>6.4.1 Number as follows when inserting a new whole provision at the beginning of an existing series of provisions (e.g. a subsection at the beginning of a section or a Schedule before the first Schedule).</p>
<ul>
<li><p>New sections inserted before the first section of an Act are preceded by a letter, starting with “A” (A1, B1, C1 and so on).</p>
</li>
<li><p>The same approach is taken in relation to all other divisions of text (other than lettered paragraphs).</p>
</li>
</ul>
<blockquote>
<p>Thus the Insolvency Act 2000 inserted a Schedule A1 before Schedule 1 to the Insolvency Act 1986, and the Enterprise Act 2002 inserted a new Schedule B1 after Schedule A1.</p>
</blockquote>
<ul>
<li><p>A provision inserted before “A1” (or “ai”) is “ZA1” or (“zai”).</p>
</li>
<li><p>In the case of lettered paragraphs, new paragraphs inserted before paragraph (a) are (za), (zb) etc.</p>
</li>
<li><p>And paragraphs inserted before (za) are (zza), (zzb) etc.</p>
</li>
</ul>
<p><strong>At the end of a series</strong></p>
<p>6.4.2 Where adding a provision at the end of an existing series of provisions of the same kind (e.g. a subsection at the end of a section or a Schedule at the end of the Schedules), the numbering should continue in sequence.</p>
<p><strong>Between existing provisions</strong></p>
<p>6.4.3 The following applies when inserting whole provisions between existing provisions.</p>
<p>New provisions inserted between 1 and 2 are 1A, 1B, 1C etc.</p>
<ul>
<li><p>New provisions inserted between 1A and 1B are 1AA, 1AB, 1AC etc.</p>
</li>
<li><p>New provisions inserted between 1 and 1A are 1ZA, 1ZB, 1ZC etc. (and not 1AA etc.)</p>
</li>
<li><p>New provisions inserted between 1A and 1AA are 1AZA, 1AZB, 1AZC etc.</p>
</li>
</ul>
<p>6.4.4 Do not generate a lower level identifier unless you have to.</p>
<ul>
<li><p>A new provision between 1AA and 1B is 1AB not 1AAA.</p>
</li>
<li><p>But a new provision between 1AA and 1AB is 1AAA.</p>
</li>
</ul>
<p>6.4.5 The above recommendations apply equally to sub-paragraphs with roman numerals and lettered paragraphs.</p>
<ul>
<li><p>New sub-paragraphs between sub-paragraphs (i) and (ii) are (ia), (ib), (ic) etc.</p>
</li>
<li><p>New paragraphs between paragraphs (a) and (b) are (aa), (ab), (ac) etc.</p>
</li>
<li><p>New paragraphs between paragraphs (a) and (aa) are (aza), (azb), (azc) etc.</p>
</li>
</ul>
<p><strong>Series of more than 26</strong></p>
<p>6.4.6 After Z use Z1, Z2, Z3 etc. For example, after section 360Z insert sections 360Z1, 360Z2 and so on; after paragraph (z) insert paragraphs (z1), (z2), (z3).</p>
<p><strong>Re-using numbers</strong></p>
<p>6.4.7 If you are inserting new text at a place where there has previously been a repeal, do not re-use the number.</p>
</blockquote>

united-kingdom england-and-wales parliamentary-procedure legislation