BOM Check for South Korea: The Letter O Is in 16 of 359,135 Walsin Part Numbers, the Letter I in 1,992, and a Cleaner That Fixes Both Breaks 1,995

A BOM check for South Korea should not blindly turn the letter O into a zero. We parsed all 359,135 distinct Walsin part numbers: the letter O is in 16 of them and the letter I in 1,992, so a cleaner that rewrites both to digits makes 1,995 real part numbers unfindable. In 2,750,811 look-alike swaps, only 6 land on another real part.

Venatech Limited, an authorised Walsin distributor in Hong Kong, holds all 203 parametric export files published by Walsin Technology (Walsin). This post is written for engineers and buyers in South Korea whose BOM reaches them from a drawing, a scanned page or a hand-keyed ERP form, where a zero and the letter O look the same on screen. It is built from the Part Number column of the eight primary export sets, read as raw characters, with the QA row Test123999 excluded. We hold no customer BOMs and describe no customer’s practice. Every part number below is real.

Which Walsin part numbers contain the letter O or the letter I?

Very few contain O, and only three of the eight families contain I. We counted every character of all 359,135 distinct part numbers: the letter O is in 16 and the letter I in 1,992, which is 1,995 parts once the 13 that hold both are counted once. The other 357,140 part numbers contain neither, so for most of the catalogue a letter O or a letter I in a BOM row is a typing slip by construction.

We have not seen this counted anywhere. The five families where the letters never occur hold 353,224 part numbers. The three where they do hold 5,911, and 1,995 of those, 33.8 percent, are damaged by the cleaner most BOM tools ship first. The 13 O-bearing inductors are the whole BIH ferrite-bead run: BIH2012OB-001H is one of 13 of 13 BIH parts with an O in position 8, and RFCON070303MF6B001 is one of three antenna-family connector codes with one.

What does an O-to-0, I-to-1 cleaner do to a Walsin BOM?

It repairs typos in five families and destroys real part numbers in three. We rewrote every O to 0 and every I to 1 in each of the 1,995 parts that contain them, then looked the result up in the export. None of the 1,995 resolves, and no rewritten string lands on a different real part either, so the failure is a clean miss rather than a wrong match. A BOM row WFI2012FS1R2K becomes WF12012FS1R2K and returns nothing.

The same test on the other six look-alike letters is a warning against widening the rule. A letter that looks like a digit is a real character in this catalogue.

Across all eight letters, 158,543 of 359,135 part numbers (44.1 percent) contain at least one, and rewriting every look-alike letter to its digit resolves none of them to a real part. Only the last two rows land on a different part, and each does so for exactly one part number in the catalogue. For the broader question of how the characters in this column behave when a BOM is re-keyed, see our post on why Walsin part numbers do not paste into your BOM.

Can a typed O for a zero land on a different real part?

No, not once in the whole catalogue. We generated every single-character swap in both directions for the O and zero pair: 298,103 part numbers contain a zero or an O, which gives 464,245 swapped strings. None of the 464,245 is a real Walsin part number. The I and one pair gives 360,054 swapped strings across 241,804 parts, and again none lands.

That means a BOM row that fails to match and holds an O where a zero belongs has exactly one possible repair, and the repair never hides a collision. The table shows the whole test for all eight pairs.

We tested 2,750,811 single-character look-alike swaps and 6 land on another real part, all of them in the RF family. The catalogue is far more tolerant of this kind of typo than its density of near-twin part numbers suggests; our post on thick-film and thin-film part numbers that differ by one character shows where the genuine one-character neighbours are, and they are not look-alike swaps.

Which Walsin part numbers differ only by a look-alike character?

Six, in three pairs, and all three pairs are RF parts. We listed every swap that lands and read both rows. In each pair the two parts share series, case size and frequency band, and differ in the figures an RF design depends on. A cleaner that picks one for you would choose silently between two different filters.

The practical rule is short. If a corrected string lands on a part in one of these three pairs, do not accept the correction automatically. Show both candidates. The 2.4 GHz chain is covered in choosing an RF chip filter by band, which also explains why the export spells the same band several ways.

What should a BOM check in South Korea do when a part number misses?

Normalise, look up, and only then try swaps. We tested the sequence against the export. Uppercase the string, strip whitespace, look it up exactly, and if it misses try one look-alike swap at a time, accepting a result only when exactly one swap resolves. On 2,750,811 tested swaps that rule gives one answer in all but 6 cases, which is why the exceptions can be named.

Three constraints keep the rule honest:

1. Never rewrite a letter globally. 158,543 part numbers contain a letter that looks like a digit, and 1,995 of them contain an O or an I that is genuine.
2. Do not treat a corrected hit as a confirmed match. A part number that resolves says the string exists; it does not say the part fits your board. The free cross-reference tool shows what matches and what differs, field by field, for the parts in the export.
3. Check the family first. In the five families without O or I, any such letter is a typo with one repair. In inductor, RF and antenna, test the string as typed before touching it.

We hold 28 Walsin datasheets, 451 pages, covering 26 MLCC and 2 chip resistor series, and we hold none for inductor, RF, antenna, varistor, disc capacitor or thin film. The inductor parts above, including the BIH run, are described only by what the export states, and that should be confirmed against Walsin’s own site. Hong Kong stock is a dated snapshot, 1,125 part numbers as at 23 September 2026, listed on ready stock. The inductor range is on the inductor page.

The short version

The letter O appears in 16 of 359,135 Walsin part numbers and the letter I in 1,992, 1,995 parts in all, and every one sits in the inductor, RF or antenna family. A cleaner that rewrites O to 0 and I to 1 repairs typos in 353,224 MLCC, chip resistor, thin film, varistor and disc capacitor parts and makes 1,995 real part numbers return nothing. Of 2,750,811 single-character look-alike swaps, 6 land on another real part, all in RF, in three pairs that differ in insertion loss or application. Do not rewrite letters globally, try one swap at a time, and show two candidates when two resolve. We tell you what the file holds. Qualification stays with you.

Send us the part number column of your South Korea BOM exactly as it leaves your spreadsheet and we will tell you how many rows are look-alike character problems and how many are real misses. And a question back: when your last import returned no match for a part with an O in it, did you check the part, or the letter?

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