<entry id="2280643" stat="A" corpus="jmdict" type="jmdict">
<ent_corp type="jmdict">jmdict</ent_corp>
<ent_seq>1487430</ent_seq>
<k_ele>
<keb>必携</keb>
<ke_pri>news2</ke_pri>
<ke_pri>nf43</ke_pri>
<ke_pri>spec2</ke_pri>
</k_ele>
<r_ele>
<reb>ひっけい</reb>
<re_pri>news2</re_pri>
<re_pri>nf43</re_pri>
<re_pri>spec2</re_pri>
</r_ele>
<sense>
<pos>&adj-no;</pos>
<pos>&n-suf;</pos>
<gloss>indispensable</gloss>
<gloss>essential</gloss>
<gloss>must-have</gloss>
</sense>
<sense>
<pos>&n;</pos>
<s_inf>usu. in book titles</s_inf>
<gloss>handbook</gloss>
<gloss>manual</gloss>
<gloss>vade mecum</gloss>
</sense>
<info>
<audit time="2013-09-08 07:28:27" stat="A" unap="true">
<upd_name>Marcus Richert</upd_name>
<upd_refs>prog</upd_refs>
<upd_diff>@@ -24,1 +24,3 @@
-&lt;gloss&gt;(something) essential to keep on you&lt;/gloss&gt;
+&lt;pos&gt;&amp;adj-no;&lt;/pos&gt;
+&lt;gloss&gt;essential item&lt;/gloss&gt;
+&lt;gloss&gt;must-have&lt;/gloss&gt;</upd_diff>
</audit>
<audit time="2013-09-08 08:14:51" stat="A">
<upd_uid>jwb</upd_uid>
<upd_name>Jim Breen</upd_name>
<upd_email>...address hidden...</upd_email>
</audit>
<audit time="2023-10-16 14:35:35" stat="A" unap="true">
<upd_name>Brian Krznarich</upd_name>
<upd_email>...address hidden...</upd_email>
<upd_detl>nikk and daijs both order them this way.  sankoku doesn't give [2] at all, but its example is [科学ー・ー書]

nikk's [2] doesn't really look like a separate sense. It reads simply: ② 特に、ハンドブック。 It does not appear from ngrams that 必携 is often used by itself to mean "book"(or that it is used as any kind of noun at all):
必携の	260221
必携が	194
必携は	722
必携を	906

For that, it also seems more useful to give [1] as an adj-gloss.

Google image search shows a lot of guidebooks self-anointing themselves with this term. For something super-modern and unremarkable, see for example a guide to HTML and CSS:
Web制作必携 HTML&amp;CSS全事典
https://book.impress.co.jp/books/1121101140

Amazon search for 必携 claims over 10,000 results... (appears almost entirely books)
https://www.amazon.co.jp/s?k=%E5%BF%85%E6%90%BA&amp;crid=J8PTAZ0XSA7U&amp;sprefix=%2Caps%2C239&amp;ref=nb_sb_noss_2

eijiro, besides "must-have" being prevalent, adds "companion".  That's pretty interesting as a noun gloss, but can't be given as an adj. Note how this is presented though:
必携
companion〔書名に使う。「～の手引」、「必携～」など。〕

English example:
The CSS Companion
200 Concepts Every Aspirant Should Know
https://foliobooks.pk/product/the-css-companion-200-concepts-every-aspirant-should-know/</upd_detl>
<upd_refs>必携	772451	 
必携の	260221	  

#1 undocumented-in-ngram use is probably book *titles* (which is also adj-f/adj-no). After that:

From the top collocations, books:
必携情報集	77764	  
必携の書	39154	  
必携の一冊	33045	  
必携書	19266	  
必携の書籍	15285	  
必携の本	8768	  
必携本	8436	  
必携の一冊です	7468	 
必携ハンドブック	3385	  
必携マニュアル	2839	  

Possibly not books:
必携アイテム	14026	  
必携のアイテム	11174	  
必携品	7569	  
必携の機能	3300	  

Reverso is all adjective usage(I include 何々は必携だ as an adj. usage: "is indispensable" vs "is an indispensable item" ). 
https://context.reverso.net/translation/japanese-english/%E5%BF%85%E6%90%BA</upd_refs>
<upd_diff>@@ -16,0 +17 @@
+&lt;pos&gt;&amp;adj-no;&lt;/pos&gt;
@@ -17,0 +19,6 @@
+&lt;gloss&gt;essential (esp. handbook, guidebook, manual, etc.)&lt;/gloss&gt;
+&lt;gloss&gt;must-have&lt;/gloss&gt;
+&lt;/sense&gt;
+&lt;sense&gt;
+&lt;pos&gt;&amp;n;&lt;/pos&gt;
+&lt;misc&gt;&amp;rare;&lt;/misc&gt;
@@ -21,6 +27,0 @@
-&lt;/sense&gt;
-&lt;sense&gt;
-&lt;pos&gt;&amp;n;&lt;/pos&gt;
-&lt;pos&gt;&amp;adj-no;&lt;/pos&gt;
-&lt;gloss&gt;essential item&lt;/gloss&gt;
-&lt;gloss&gt;must-have&lt;/gloss&gt;</upd_diff>
</audit>
<audit time="2023-10-17 03:08:10" stat="A">
<upd_uid>jwb</upd_uid>
<upd_name>Jim Breen</upd_name>
<upd_email>...address hidden...</upd_email>
</audit>
<audit time="2023-10-18 23:16:48" stat="A" unap="true">
<upd_uid>robin1354</upd_uid>
<upd_name>Robin Scott</upd_name>
<upd_email>...address hidden...</upd_email>
<upd_detl>Book titles are sense 2. Sense 1 is usage like "学生必携の書. a book indispensable to students" or "防寒具必携のこと. Warm clothing is a must".</upd_detl>
<upd_refs>gg5
smk: いつも持っていなければならない（た方が便利な）こと。また、そういう物。〔ある専門の入門書の名前に付けることが多い。例、「化学―」〕「―の書」
prog: 英会話必携  a handbook of English conversation</upd_refs>
<upd_diff>@@ -18,2 +18,3 @@
-&lt;pos&gt;&amp;n;&lt;/pos&gt;
-&lt;gloss&gt;essential (esp. handbook, guidebook, manual, etc.)&lt;/gloss&gt;
+&lt;pos&gt;&amp;n-suf;&lt;/pos&gt;
+&lt;gloss&gt;indispensable&lt;/gloss&gt;
+&lt;gloss&gt;essential&lt;/gloss&gt;
@@ -24 +25 @@
-&lt;misc&gt;&amp;rare;&lt;/misc&gt;
+&lt;s_inf&gt;usu. in book titles&lt;/s_inf&gt;</upd_diff>
</audit>
<audit time="2023-10-19 21:53:19" stat="A">
<upd_uid>jwb</upd_uid>
<upd_name>Jim Breen</upd_name>
<upd_email>...address hidden...</upd_email>
</audit>
</info>
</entry>