Construction Confusion

Now that the next Jane Austen Festival has been announced, I am scheming about NEW costumes! They may not be realized, because I have to finish last year's pieces first, but one can always scheme.

I would love to put together for myself a slightly more "working woman" impression, with a simple cotton dress and a cotton/linen spencer. It would be a fun exercise in print-mixing. With that in mind, I have been researching cotton print spencers, and I came across one that I really love, but the construction baffles me. I am trying to puzzle out how, exactly, it opens to be put on.

From the front view, I can decipher:
- The top of the bodice and the "skirt" (below the bust line) appear to be separate pieces of fabric. I can't tell, however, if they are gathered separately before being assembled, or if all the gathers at the front are caused by a little hidden drawstring. When I compare the shirring ratio on the upper bodice to the shirring ratio on the "skirt," they appear to have been gathered separately before being stitched together.
- The sleeves are cut in one piece on the fold/straight grain, but they are shaped to narrow at the wrist before flaring out over the knuckles.
- There are two little ties hanging down at the sides of the garment. From the front, I have no idea what purpose these serve, but you can see them a little better on the back.
- There is green trim around the neckline and sleeve hems.
- The bodice appears to be lined at the back, and it looks flat (as though the center-back gathers we see on the back view are only in the fashion fabric, mounted on a fitted lining.)

Jak, Blaricum via the Nederlands Openluchtmuseum

The back of the spencer provides a little more construction information:
- The back bodice is cut extremely narrow, and is tightly gathered. I wouldn't call the gathers "full," though, as there is no body to them (they're very flat - which would support my conjecture that this piece is mounted on a fitted lining).
- There are small (1.25"?) rectangles of fabric covering the shoulder seams, which are placed very far back.
- There is a seam (which appears to have a narrow self-fabric piping) between the upper bodice and lower bodice/skirt. This piece is flat, with no gathers in the upper or lower edges.
- There is another seam bisecting the lower half of the bodice. This piece is definitely gathered at center back, and has a little bit of green trim at the bottom edge, which cuts off before reaching the sides of the bodice.
- There are three brass (pewter? some kind of metal) buttons mounted on the lower seam. These buttons appear to be non-functional, entirely decorative.
- The green trim extends all the away around the back neckline (the entire neckline is trimmed).
- The bodice appears to be unlined on the front (the front skirt, at least).
- There appears to be an opening at the side seams, from which the striped (linen?) tapes hang! This part puzzles me the most. I have never seen a side opening like this that doesn't have some kind of apron-front piece on the front, allowing for more flexibility. Do the openings extend from hem to sleeve? Is there any kind of slit in the sleeve for flexibility? Why are the openings there instead of CF or CB? Was this common and I just never realized it? How do the ties get tucked away when the jacket is worn? Where is the front set of ties disappearing under the bodice in this picture? So many questions.

Jak, Blaricum via the Nederlands Openluchtmuseum

Also, what is that green trim made of? It almost looks like cotton fabric with trapunto stuffed rows. Or maybe they are just corded! But the trim doesn't appear to be stiff (if you look at the gathered back skirt, it folds pretty easily).

This jacket is what I am puzzling over today. I think I might have to reproduce it; it is too interesting to not investigate with a reproduction.