# What is the rationale for only marking certain letters with sheva, when they are the last letter in a word?

In printed and manuscript editions of Tanach, I've noticed that a sheva on the final letter of a word is almost never marked, and is meant to be inferred.

The two exceptions I've come across are:

1. A final chaf e.g.

Bereishit 1:2 (among very many):

וְהָאָ֗רֶץ הָֽיְתָ֥ה תֹ֨הוּ֙ וָבֹ֔הוּ וְחֹ֖שֶׁךְ עַל־פְּנֵ֣י תְה֑וֹם וְר֣וּחַ אֱלֹהִ֔ים מְרַחֶ֖פֶת עַל־פְּנֵ֥י הַמָּֽיִם׃‏

1. A plosive letter e.g.

וַיִּשְׁמַ֞ע הַכְּנַֽעֲנִ֤י מֶֽלֶךְ־עֲרָד֙ יֹשֵׁ֣ב הַנֶּ֔גֶב כִּ֚י בָּ֣א יִשְׂרָאֵ֔ל דֶּ֖רֶךְ הָֽאֲתָרִ֑ים וַיִּלָּ֨חֶם֙ בְּיִשְׂרָאֵ֔ל וַיִּ֥שְׁבְּ ׀ מִמֶּ֖נּוּ שֶֽׁבִי׃‏

וַיִּ֣חַדְּ יִתְר֔וֹ עַ֚ל כָּל־הַטּוֹבָ֔ה אֲשֶׁר־עָשָׂ֥ה יְהוָ֖ה לְיִשְׂרָאֵ֑ל אֲשֶׁ֥ר הִצִּיל֖וֹ מִיַּ֥ד מִצְרָֽיִם׃‏

לְהוֹדִֽיעֲךָ֗ קֹ֭שְׁטְ אִמְרֵ֣י אֱמֶ֑ת לְהָשִׁ֥יב אֲמָרִ֥ים אֱ֝מֶ֗ת לְשֹֽׁלְחֶֽיךָ׃‏

וַיִּשַּׁ֥ק יַֽעֲקֹ֖ב לְרָחֵ֑ל וַיִּשָּׂ֥א אֶת־קֹל֖וֹ וַיֵּֽבְךְּ׃‏

אַל־תּ֥וֹסְףְּ עַל־דְּבָרָ֑יו פֶּן־יוֹכִ֖יחַ בְּךָ֣ וְנִכְזָֽבְתָּ׃‏

וַיָּבֹ֥אוּ הָֽרֹעִ֖ים וַיְגָֽרְשׁ֑וּם וַיָּ֤קָם מֹשֶׁה֙ וַיּ֣וֹשִׁעָ֔ן וַיַּ֖שְׁקְ אֶת־צֹאנָֽם׃‏

Bereishit 12:11 (among many):

וַיְהִ֕י כַּֽאֲשֶׁ֥ר הִקְרִ֖יב לָב֣וֹא מִצְרָ֑יְמָה וַיֹּ֨אמֶר֙ אֶל־שָׂרַ֣י אִשְׁתּ֔וֹ הִנֵּה־נָ֣א יָדַ֔עְתִּי כִּ֛י אִשָּׁ֥ה יְפַת־מַרְאֶ֖ה אָֽתְּ׃‏

What is different about these cases that means that the sheva is marked?

• In the latter case,the shva is arguably na'. Only a shva nach is customarily omitted (hence the common name of the phenomenon "nach nistar") – Double AA Nov 14 '20 at 23:00
• I have a vague recollection of seeing a final mem (at the end of a word) with a sh'va printed, somewhere in Tanach. I could be misremembering (and I've no idea what that would mean different from a regular final mem, anyway). – msh210 Nov 14 '20 at 23:02
• @msh perhaps thinking of he.wikisource.org/wiki/… where the printer had the vowels over the ktiv or something like that? – Double AA Nov 15 '20 at 0:24
• @DoubleAA Why would the sheva in ויחד or את be na’? – Joel K Nov 15 '20 at 11:37