Column internal names: SharePoint derives them from the label, whatever your XML says
Adding a field to a list with createfieldasxml and Options: 0 ignores Name and StaticName in your schema XML and builds the internal name from DisplayName — so a localized label leaves you with _x00da_tvar forever. Create the field with an ASCII DisplayName and rename its Title, or pass Options: 8 (AddFieldInternalNameHint) and Name is used as given. The internal name is fixed at creation, the label is not.
Když přidáváš pole do seznamu přes createfieldasxml, SharePoint Name ani StaticName ze schématu nepoužije a interní název odvodí z DisplayName – z lokalizovaného popisku ti tak napořád zůstane _x00da_tvar. Zakládej s ASCII DisplayName a hezký Title nastav až potom, nebo pošli Options: 8 (AddFieldInternalNameHint) a SharePoint Name použije. Interní název je dán okamžikem vzniku, popisek ne.
Symptom
You create columns with explicit internal names:
<Field Type='Choice' Name='Utvar' StaticName='Utvar' DisplayName='Útvar' Format='Dropdown'>…</Field>The call returns 200, and the response says InternalName: "_x00da_tvar". Same for
Typ dokumentu → Typ_x0020_dokumentu. Every formatter, CAML query and $select you write
afterwards has to carry those escapes.
Cause
Name/StaticName are honoured for site columns (/_api/web/fields), but when a field
is added to a list, SharePoint generates the internal name from the display name, percent-
escaping anything outside A–Z a–z 0–9 as _x00xx_ (Ú → _x00da_, space → _x0020_).
It is the same rule that gives a list its URL from its title — and it is equally permanent:
renaming the column later changes only the label.
Fix
Create with an ASCII display name, then set the real one:
// 1) create — DisplayName decides the internal name
const r = await sp.post(`${web}/_api/web/GetList('${listRel}')/fields/createfieldasxml`, {
parameters: { SchemaXml: "<Field Type='Choice' DisplayName='Utvar' Format='Dropdown'>…</Field>", Options: 0 }
});
const internal = (await r.json()).InternalName; // "Utvar"
// 2) rename — label only, internal name stays clean
await sp.post(`${web}/_api/web/GetList('${listRel}')/fields/getbyinternalnameortitle('${internal}')`,
{ headers: { 'IF-MATCH': '*', 'X-HTTP-Method': 'MERGE' }, body: JSON.stringify({ Title: 'Útvar' }) });Or keep the source name: Options: 8 (AddFieldInternalNameHint)
When you must reproduce an existing internal name (copying a list's schema to another site,
where mappings and lookups refer to the source names), the ASCII-then-rename trick cannot
produce Z_x00e1_kazn_x00ed_k. Pass Options: 8 (AddFieldInternalNameHint) and SharePoint
uses Name from the XML. Measured 2026-10-27 on a list:
| SchemaXml | Options | InternalName returned |
|---|---|---|
Name="Z_x00e1_kazn_x00ed_k" DisplayName="Jiný popisek" |
8 | Z_x00e1_kazn_x00ed_k |
Name="StavX" DisplayName="Stav úkolu" (Choice) |
8 | StavX |
Name="Kod_x0020_A" DisplayName="Bez hintu" |
0 | Bez_x0020_hintu |
await sp.post(`${listApi}/fields/CreateFieldAsXml`, {
parameters: { SchemaXml: "<Field Type='Text' Name='Zakaznik' StaticName='Zakaznik' DisplayName='Zákazník' />", Options: 8 }
});Still compare the returned InternalName with what you asked for — if the name is already
taken in the list, you get a suffix instead (see field-created-twice-gets-a-numeric-suffix.md).
Why it is worth the extra call
Internal names are what everything else refers to: [$Utvar] in view formatting, $select,
CAML <FieldRef Name>, Search managed-property mappings, PnP templates. [$_x00da_tvar]
works, but every future author has to know why it looks like that — and escapes are easy to
mistype in JSON where you get no error, just a silently empty column.
Rule
Anything whose URL or internal name is generated from a label — lists, columns, content types — should be created under an ASCII name and renamed afterwards. Decide the machine name at creation, because that is the only moment you control it.