Iambic pentameter
does not quite work for this here
idea. For seven lines
of fourteen syllables does
not seven by seven make.
So if only fourty-nine,
free flowing or strict line time?
Really, I think of the form like a sonnet: the syllabic structure is always the same, but the rhyming requirements change [see the difference between a Shakesperean and Italian sonnet]. Potential schemes:
a-b-c-d-e-f-g
a-b-c-d-c-b-a
a-a-b-b-b-c-c [c could also be a]
a-a-a-b-c-c-c [where c is neither a nor b]
a-b-a-b-a-b-a
a-b-b-a-b-b-a
etc. So many possibilties! That also leads to the question: you could define it by flow instead of rhyme. Or simply be like haiku: a picture-thought that simply has the number of lines with their number of syllables. I'd name them 'septic', but that's been taken and has a rather negative connotation
I think I'll refer to them as septisyllabic septets for strict accuracy of defining the form for now.