title_body: Syllabic restriction/word boundaries set by IPA? Or it is decided by language creator When creating syllables we basically require an onset, nucleus, and a coda. Now, usually, all language have an onset, and the coda is fairly optional. Before creating a phonetic system, we first decide the word order, and rules about what sounds are allowed in the onset, nucleus and coda positions.
  My question is focused on the 2nd part. For example, in English, the sound [ŋ] isn’t allowed to begin a word, but it can begin a syllable; and in Dothraki, the consonants, &lt;I couldn't find the symbol&gt;, [q], and [w] can’t end a word.
  So these restrictions, do they arrive because of some IPA rule? Or is it the developer that creates these rules?
upvoted_answer: The phonotactics of a language, what you have described, is the silent partner of phonology. The analogy I like to use is that a language's phonology is its periodic table (with individual phonemes as individual elements), while its phonotactics are the entire rest of its chemistry. Higher level stuff, like morphology, semantics, pragmatics, are things like biology, psychology, sociology.
  Just like every language has its own phonology, every language has its own phonotactics.  There are languages that can put /ŋ/ in onset (for example, Vietnamese) or /h/ in coda (Arabic). There are languages that can't make /s/ clusters, or any clusters for that matter (Hawaiian).
  The IPA is the &quot;Grand Unified Periodic Table of Linguistics&quot;; it's stated purpose is to label every sound used in a human language, and does not restrict their arrangement in anyway. There is no &quot;Grand Unified Chemistry of Linguistics&quot;; phonotactic laws are usually described in plain language, although there is a notation to succinctly describe allophonic variation (that is, how phonemes are realized as phones in different environments) and phonemic evolution (how a language's phonemes evolve over time).