Some parse structures are recognised, built and then cut out structures such as adverbial phrases, prepositional chains comprising prepositionals, adjectivals and participials, and parenthetical phrases and negation. Cutting out the symbol and healing across the gap means that the grammar can be simpler - it doesn't have to handle the possibility of all these different phrases occurring at every position in the sentence.
The local structure is cut out and used to modify another symbol in the structure, with the cut section healed by joining both sides of the cut. This means that, at the level of the PARSE operator, a word acquires a new neighbour and the cutting of alternatives needs to be redone. Adverbial phrases, in particular, can appear almost anywhere in a sentence.
Quickly, John ran to the shop.
John quickly ran to the shop.
John ran quickly to the shop.
John ran to the shop quickly.
and for parentheticals
Quickly, John (the boy next door) ran to the shop.
John quickly ran to the shop (the one at the end of the road).
The apparent freedom of position implies that any initial alternatives cutting based on the presence of these phrases must be minimal and recoverable (an adverb is made to be compatible with word, meaning anything). The adverbial phrase is first recognised, a structure built on it, the BRIDGE operator recognises this structure as one to be cut out,
and then it is cut out and turned into a modifier (what it modifies may differ based on its position, but the point here is that it is cut out). The PARSE operator at the site of the repair now has to cut alternatives based on the new word neighbours (taking into account any higher level structures that may already be linked to its symbol node).
The cutting process will recur as soon as the prepositional phrase "out the door" is recognised, so the final sentence structure will be
with both an adverbial and a prepositional modifier on "walked".
The modifiers are honoured during the building of the semantic structure.
A long sentence may have a dozen cutting and healing operations on it, together with as many insertions, for implied symbols.