The EL plural morpheme may be seen as part of the selected EL content morpheme. It is not syntactically active and, as a result, the ML plural morpheme is provided as well.
The insertion of single words, as in (1b), is seen as resulting in ML + EL constituents, which must adhere to two principles: the morpheme order principle stipulates that the ML sets the morpheme order, and the system morpheme principle that content morphemes can come from the EL, but that a certain type of functional element (here called system morphemes) has to be from the ML.
Formation of compounds is mainly a matter of juxtaposing two content morphemes. In most cases, alternatives can be imagined fairly easily, but, for some reason or other, these were not coined.
Thus, a content morpheme in one language may have a counterpart in another language that is a system morpheme, or may even have no counterpart in terms of matching morphemes.
Their form depends on the grammatical configurations that the language-specific grammar requires of that projection, not on the content morpheme that is the head of that maximal projection, as is the case with "early" system morphemes.
The preposition down is a content morpheme in Stella stood down by the riverside, but it is an early system morpheme in Stella laid the bone down/Stella laid down the bone.
Consequently, if an outsider late system morpheme is part of a multimorphemic word that contains either a content morpheme or an early system morpheme, it blocks directions from these conceptually activated morphemes.
However, the embedded language, English, can supply the adjective silly, a content morpheme. In (11) and (12), English is also the embedded language and therefore can supply the content morphemes ship and buy and father.
It is only through mistiming that the embedded language supplies an early system morpheme along with the embedded-language content morpheme that is its head.
It is easy to see how, through mistiming, an early system morpheme is accessed along with its embedded-language content morpheme head -- even though the frame of the constituent -- because it is under matrix-language control and therefore prefers matrix-language system morphemes -- does not call for an embedded-language inflection.