# Mandatory symbol parameters (.SchLib)

Vecmocon's Altium SOP (§5) requires every schematic-library symbol to carry a fixed set of
parameters in its component properties (the panel shown in Altium: *Properties → Parameters*).
This file defines that set, where each value comes from, and how the skill stamps them onto the
`.SchLib` symbol.

How the parameters get in: the skill writes them **directly into the `.SchLib` in pure Python**
via `scripts/schlib_write.py` — it rebuilds the OLE compound file around the enlarged component
`Data` stream while preserving every other byte (all other streams, the directory tree, the
Altium CLSIDs). It also **removes the Ultra-Librarian default params `Manufacturer_Name` and
`Manufacturer_Part_Number`** (which duplicate the SOP `Manufacturer` / `Manufacturer Part`), the
UL **`Copyright`** notice (Vecmocon symbols don't carry it), and the UL **`Component_Type`**
(underscore) — replaced by Vecmocon's own spaced **`Component Type`** parameter (see below).
The output is a ready `.SchLib`. Because this writes Altium's own format from outside Altium, the
script self-checks that the result re-opens as a valid OLE with the params present — but **always
open the result in Altium once to confirm it loads** before relying on it. (An older path,
`scripts/altium_params.py`, instead emits an Altium DXP script to stamp the same parameters from
inside Altium; keep it as a fallback if a particular file doesn't round-trip.)

## The parameter set

Use these exact Altium parameter names (they must match the symbol, per the SOP screenshot).
The **Comment** field is set to the MPN (SOP §4), and the **Description** field is the strict
string from `references/description_format.md`.

**The Description is not a parameter record.** It is the `ComponentDescription` field of the
component's `RECORD=1` header — the box shown at *Properties → General → Description*, above the
Parameters table. Ultra-Librarian ships it as the literal placeholder text `Description`, so a
symbol whose parameters are all correctly filled will *still* show the word "Description" in
Altium unless that header field is rewritten. `schlib_write.py` now sets it in the same pass as
the parameters: pass `"description"` in `params.json`, or let it fall back to your
`parameters.Description`. Always give it the same strict `Class_TYPEID` string you wrote into the
part's Excel, so the symbol and the workbook agree.

| Parameter | Source | Notes |
|-----------|--------|-------|
| `Component Type` | derived | the part's **Class** — `Resistor`, `Capacitor`, `Diode`, `Transistor`, `IC`, … — from the taxonomy row for its typeid (`scripts/common.py:class_folder(typeid)`) |
| `Value` | datasheet | the component **value only** (no package), in shorthand — e.g. `1u`, `12p`, `100n`, `10k` |
| `Manufacturer Part` | datasheet | the MPN; also the **Comment** field |
| `Manufacturer` | datasheet | manufacturer name as printed, e.g. `YAGEO` |
| `Manufacturer Part 2` | **leave blank (for now)** | second-source MPN — left empty by default; see optional note below |
| `Manufacturer 2` | **leave blank (for now)** | second-source manufacturer — left empty by default |
| `Process` | derived | assembly process from package: SMD → `Reflow`, through-hole → `Wave`/`Manual`; confirm |
| `Vecmocon Part Code` | engineer | internal code (e.g. `VECESC2421`) — **not on the datasheet**; ask |
| `Operating Temperature` | datasheet | full range, e.g. `-55 °C to +125 °C` |
| `Tolerance` | datasheet | e.g. `1%` (or `±1%`) |
| `Datasheet` | datasheet | source URL or document reference (SOP marks this optional) |
| `ROHS` | datasheet | RoHS compliance, `Yes`/`No` |

**Read the datasheet-sourced values from the actual datasheet — don't echo whatever text was
handed to you.** Open the PDF, find each real value (`Value`, `Manufacturer Part`,
`Manufacturer`, `Operating Temperature`, `Tolerance`, `Datasheet`, `ROHS`, and `Process` by
inference from the package), and fill them verified. An honest blank beats a guess — the SOP
hides blank parameters, so a gap just stays empty until someone fills it. Only **one** field is
purely internal and must come from the engineer: `Vecmocon Part Code` — ask for it.

The second-source pair (`Manufacturer 2` / `Manufacturer Part 2`) is **left blank for now** —
don't populate it by default. It simply stays hidden in Altium until someone fills it later.

## Optional: second-source cross-reference (currently off)

**House preference right now is to leave `Manufacturer 2` / `Manufacturer Part 2` blank**, so do
not do this unless the engineer explicitly asks you to find a second source. It's documented
here so it can be switched on later without redesigning anything.

If asked to find a second source, it is an **equivalent part from a different manufacturer** that
could drop into the design unchanged:

1. **Pull the original's form-fit-function specs** from the datasheet — capacitance, voltage,
   tolerance, dielectric/temp class, package (for a cap); resistance, power, tolerance, package
   (for a resistor); and so on per type.
2. **Search for an equivalent from a *different* manufacturer** (distributor/parametric
   cross-reference, "equivalent to `<MPN>`", or another reputable maker's matching series). It
   must match **every** form-fit-function spec and be **at least as good** on tolerance /
   voltage / temperature — never worse.
3. **Fill** `Manufacturer 2` = its maker, `Manufacturer Part 2` = its exact MPN.

Two hard rules if this is ever used: **never invent an MPN** (only a part number you verified
exists; else leave blank), and **always flag the chosen second source for the engineer to
confirm** with the specs you compared.

## Building the parameter set

Collect the values into a `params.json` (same spirit as `part.json`). `component` is the
symbol's Library Ref (from `altium_refs.py`); omit it to apply to every component in the lib.

```json
{
  "component": "CC0402FRNPO9BN120",
  "comment": "CC0402FRNPO9BN120",
  "description": "Capacitor_CER_12pF_50V_±1%_0402_NPO",
  "parameters": {
    "Component Type": "Capacitor",
    "Value": "12pF_0402",
    "Manufacturer Part": "CC0402FRNPO9BN120",
    "Manufacturer": "YAGEO",
    "Manufacturer Part 2": "0402N120F500CT",
    "Manufacturer 2": "Walsin Tech Corp",
    "Process": "Reflow",
    "Vecmocon Part Code": "VECESC2421",
    "Operating Temperature": "-55 °C to +125 °C",
    "Tolerance": "1%",
    "Datasheet": "https://www.lcsc.com/datasheet/C326662.pdf",
    "ROHS": "Yes"
  }
}
```

## Writing them into the symbol

Write the parameters straight into the `.SchLib`, producing a new file:

```bash
python scripts/schlib_write.py --schlib <in>.SchLib --params params.json --out <out>.SchLib
```

`params.json` may carry a `"remove"` list (defaults to `["Manufacturer_Name",
"Manufacturer_Part_Number", "Copyright", "Component_Type"]`); those Ultra-Librarian defaults are
stripped and the SOP params — including the spaced `Component Type` = Class — added. The script targets the component named in `"component"` (its Library Ref / storage name),
or every component if omitted, and self-checks the output re-opens as a valid OLE. Deliver the
resulting `.SchLib`, and have the engineer open it in Altium once to confirm it loads, then Save
to Server with a revision note per the SOP.

Scope note: the d