Abbreviating sets of compounds with leading characters in common I recently asked a question about on- and kun-yomi and in building the title guessed at how the two compounds involved could be contracted; landing on . Is this indeed the correct way of abbreviating something like , and if so, when can it be used? If not; what construction should be used?

In general, there is no restriction in making this kind of ad hoc portmanteau compounds, as long as all original words have parallel structure. That said, it's more natural if the non-common parts are contrastive in meaning.

> "water(works) and sewerage" < +
> "opening and closing ceremony" < +
> "visuo-haptic" < +

It doesn't need to be exactly two components:

> "seat of the office of ///" (i.e. capitol)

or being the first character:

> "import and export" < +

But an interpunct () is required when the result spelling causes confusion (colliding with existing words):

> {}{} "North and East Asia" cf. {} "northeast"
> 12 "the ring road 1/2"

In your case, however, the word is already reserved for "a type of 2-kanji word where the former is read in and the latter in ", so you should avoid this wording (but should be understood with aid of the context). Fortunately, as mentioned in a comment, what you mean can be conveyed by another word .