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Optical slack

Slack — the spare length of cable coiled and stored at a point so that it can be re-spliced later.

  • Georgian: მარაგი (matching the field's Russian запас, "reserve")
  • Full form: ოპტიკური მარაგი

Why it exists

If a cable is pulled to exactly the length needed, any future intervention — a new joint closure, repairing damage, adding an element — means cutting the cable and re-pulling it. Slack solves that: a coil left in advance lets a technician bring the cable down to the manhole or the pole and work on it in place.

FiberQ's default when generating slack in batch: 20 m.

Two types that must not merge

The maintainer warns separately: translating both with one word is not acceptable.

Terminal slack — slack at a cable end.

  • Legacy name: end slack, internally zavrsna
  • Drawn as a C coil
  • Georgian: საბოლოო მარაგი (expanded form: საბოლოო წერტილის მარაგი)

Mid span slack — slack at an intermediate point where the cable runs through without being cut.

  • Legacy name: thru slack, internally prolazna
  • Drawn as an S coil
  • Georgian: შუალედური მარაგი
flowchart LR
    A["cable end"] --- B["intermediate point"] --- C["cable end"]
    A -.->|"C coil"| SA["terminal slack"]
    B -.->|"S coil"| SB["mid span slack"]
    C -.->|"C coil"| SC["terminal slack"]

How to remember it

Terminal = the cable ends here. Mid span = the cable passes through. span is the run between two points — not a bridge span.

The FiberQ tools

String Georgian What it does
Place terminal slack (interactive) საბოლოო მარაგის განთავსება (ინტერაქტიული) You click the spot yourself
Place mid span slack (interactive) შუალედური მარაგის განთავსება (ინტერაქტიული) Same, for the mid-span type
Generate terminal slacks at the ends of selected cables საბოლოო მარაგების გენერირება მონიშნული კაბელების ბოლოებზე Batch — both ends of every selected cable at once
Optical slacks ოპტიკური მარაგები The tool group and the layer it writes to
Terminal slack (shortcut) საბოლოო მარაგი (მალსახმობი) A hidden action that exists only to bind the R key

\"(shortcut)\" is a key binding, not a file

Terminal slack (shortcut) does not appear on the toolbar — it shows up in the QGIS keyboard-shortcuts list. "Shortcut" here means the key binding, not a Windows shortcut file.

Validation on slack

Two rules touch slack:

  • Optical slack references an existing cable — a slack record must not be orphaned
  • In the length checks: total_len_m must equal duzina_m + slack_m

So slack is stored in its own field and counts toward the cable's total length.

Recalculating lengths does not change slack

The Recalculate lengths dialog says so directly: "Slack values are read but never changed."