Channel Fields and Placeholders

The Fields tab maps each feed column to product data, AI content, or static text — this article covers field anatomy, nested blocks, chaining fallback content, and the "Require content for this placeholder" toggle.

Updated September 3, 2026

What a field is#

A field is one column (feed element) in your channel's output — for example g:title, image_link, or video/url. Destinations expect specific element names and value formats, so a field's name must match what the destination's spec calls for:

Open the Fields tab on a channel to see the full list. Each field has:

  • Type icon — Text, Image, Video, or Voice over (audio) — the same content types used for Studio placeholders. A fifth type, Nested block, writes a block of child elements instead of a single value (see below).
  • Field name — free text; this is what ends up in the exported feed, so it must match the destination's expected name exactly.
  • Field content — the same placeholder editor used in Studio templates, where you build the value from static text, product data, or content elements.
  • Repeated names — a channel may hold several fields with the same name; Meta's image blocks are the usual case, and the order they appear in is what the destination reads as their position.
  • Numbered labels — because a repeated name is ambiguous on screen, Renable labels those fields image · #1, image · #2, and so on, wherever one is named: the Fields tab, a rule's field pickers, the TRACE dialog, a run's per-field statistics, and when Aimée talks about a run. The number is a label, not a value: it is counted in field order and never reaches the feed, so it is not the destination's own position number for the field. The number is a label only: it isn't part of the field name and never reaches the feed.
  • Allow multiple values — a switch that lets a field repeat instead of carrying a single value, for feed elements that accept several entries per product, like additional_image_link. On a nested block it means something slightly different — the block repeats — which the nested-block section covers.

Adding a field#

Click Add field in the last row of the fields table, give it a name and type. The field is created empty — you add its content afterward using the field-content editor. The type isn't final: a field's own menu has Change type, which leaves the content in place and changes which content elements it offers. (A nested block is the exception — that's chosen at creation, because a block holds sub-fields rather than a value.)

Nested blocks#

Most feed columns carry one value. Some carry a block of child elements instead — Google's grouped attributes like g:product_detail and g:question_and_answer, and Meta's image block, which pairs an image URL with the tags that name it.

Pick Nested block as the field's type when you create it. The row then shows a nested chip and, under it, one row per sub-field of the block: a name (the child element, lowercase letters, numbers and underscores) right under the field's own name, and its own placeholder expression beside it.

Add sub-field opens the same short form Add field does — a name and a type — titled Create sub-field. Picking the type here matters: it decides which content elements the sub-field's expression offers, so an image sub-field can be pointed at a product photo or a rendered template, and a text one can't. A sub-field can't itself be a nested block, so that type isn't offered. Each sub-field's own menu carries Remove sub-field.

A few things about sub-fields are worth knowing:

  • Sub-field names may repeat. Two sub-fields both named tag emit two <tag> children — that's how one block carries several tags, and it isn't a mistake to correct.
  • A sub-field with no value is left out of its block. The block still keeps its shape; the empty child just isn't written.
  • A block can carry at most one image or video sub-field. Once one sub-field has that type, the Image and Video options are disabled in Create sub-field and say which sub-field already holds the slot. An image design and a video design are two separate nested fields.
  • You can change a sub-field's type later, from its own menu, exactly as you can a field's. Changing the type doesn't clear what you've built — it changes which content elements the expression offers, so a binding the new type can't offer stays there for you to replace. What you can't change either way is whether something is a nested block: that's delete and add again.

A channel rule can point at a nested field, but not in the way it points at an ordinary one: instead of setting a value it replaces the whole block for the products the rule matches. If you later delete that field, or turn it back into an ordinary one, the rule stops doing anything and the channel raises a warning saying so — nothing breaks, but nothing happens either until you repoint or remove the rule. See Channel automations. A rule's condition still can't read a nested field — a block isn't a value to compare — so nested fields don't appear in the condition picker.

Repeating a block#

Turn on Allow multiple values on a nested field and the block repeats — one block per item of a list, capped by Max blocks. This is how a Q&A or attributes column emits one block per question or per attribute. Leave it off and the field writes exactly one block per product; several blocks of the same name are then several same-named fields, in field order.

The switch is only offered when repeating would actually work, and when it's unavailable the row says which of three reasons applies:

  • The sub-fields don't read a list. Repeating needs something to repeat over, so at least one sub-field has to be bound to a list — for example "Product attribute name". The switch tells you to pick one.
  • The sub-fields read different lists. There's no single thing to repeat over, and picking one for you would mispair every block. Point the repeating sub-fields at the same list.
  • The output format can't carry it. CSV and TSV have a fixed header row per feed, and a repeating block produces a number of columns that depends on each product's data. A single nested block is fine on those formats; only a repeating one isn't. Switch the channel's format to XML or JSON on the Settings tab — the format options that can't carry it are disabled there, with the same explanation.

You never pick the list to repeat over yourself: Renable works it out from the sub-fields, and keeps the sub-fields and the list in step.

Design blocks#

Meta's image and video blocks are the same mechanism with a specific shape, and they have their own management surface — the Adaptive designs dialog, which builds and names them for you rather than leaving you to hand-author sub-fields. See Adaptive designs.

On a channel using adaptive designs, the Fields tab doesn't list those blocks one by one. They collapse into a single Adaptive designs row in the Media group, which counts them and opens the dialog; Show raw fields on that row expands them as ordinary field rows, each back in its own position in the field list, when you want to edit one by hand. They're still normal fields — the row is a shortcut past a dozen of them all named image, not a lock. Only blocks Renable built for adaptive designs go into it: a nested block you added yourself stays exactly where you put it.

One rule applies to any block carrying media: at most one sub-field per block may produce an image or a video. Two would compete for the same position in the destination's list, and an image beside a video matches no block shape Meta defines. An image design and a video design are two separate nested fields.

Changing your mind#

There's no switch that un-nests a field: delete it and add it again as the type you want. The two shapes carry different content — a value versus a block of sub-fields — so there's nothing meaningful to convert between.

Building field content#

Click into a field's content editor to build its value:

  1. Type static text directly, or
  2. Use the dropdown (down-arrow) to insert a content element — AI-written ad copy, review extracts, product data like price or ID, or a templated image/video. See Available placeholders for the full catalog.
  3. Chain a fallback placeholder after it. A fallback's value is only used if everything before it resolves empty — so you can build a chain like "AI headline → product title → static text" that always produces some value.

Several of the fields a new channel starts with are already built this way. The condition field, for example, uses your catalog's own condition value and falls back to new for products where that value is missing or blank, so the field is never exported empty.

Require content for this placeholder#

Click a content-element chip inside a field's editor to open its settings. Each content element has a toggle:

  • "Require content for this placeholder" — shown when the element has no fallback chained after it.
    • On: if this element (and any fallback chain before it) can't resolve a value, the field counts as missing content for the channel. This is what the built-in Status automation and the channel's Activity tab react to — for example, archiving the product or raising a warning when required content isn't there.
    • Off: if the product doesn't have this content, the field is simply left empty — it does not count as missing content, so it won't trigger the Status automation or a missing-content warning. Use this when an empty value is normal and shouldn't affect the product's status (for example, an optional field that many products legitimately don't have).
  • If a fallback is chained after the element, the toggle's label changes to "Fallback to the next placeholder if this content is missing" instead — same underlying behavior, phrased for the chain.

This is the current name and behavior of this control. If you're following older instructions that mention a checkbox called "Allow value to be missing," that's the same setting under its current name.

Deleting a field#

The delete button on a field is disabled, with a tooltip explaining why, if that field is referenced by a channel automation's trigger or action. Remove or repoint the automation first, then delete the field.

Fields are draft-first#

Like everything else on the channel page, field changes save automatically to a draft — the live feed doesn't change until you publish.

Where to go next#