# H4 Empty Attribute Value Report

> H4 Empty Attribute Value Report is a paid API for AI agents from market.datapackvibe.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-12).

Parses H4 heading elements from a webpage or HTML snippet and reports which ones have empty values for a specified HTML attribute.

## Facts

- Endpoint: POST https://market.datapackvibe.com/x402/assistant-bx-web-h4-empty?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/h4-empty-attribute-value-report-7da2056d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_fRdEKsuf_5zDqvLZUcnxI

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability h4-empty-attribute-value-report-7da2056d -d '<json body>'
```

Example prompt: Can you check https://example.com/docs for any H4 headings that have an empty 'id' attribute, looking specifically for headings related to 'product'?

## When to prefer this

Use this endpoint when you need a focused, low-cost static analysis of H4-level heading attribute emptiness specifically — particularly when you want to audit a single page's fourth-level headings for missing or blank attribute values without needing JavaScript execution, login access, or full-page structural analysis.

## Known failure modes

- URL is unreachable or returns non-200 status — report may be empty or error returned
- HTML exceeds 100,000 character limit — request rejected
- Attribute name does not match pattern ^[a-zA-Z][a-zA-Z0-9:_-]{0,49}$ — validation error
- Page requires JavaScript rendering — dynamic content not captured
- No H4 elements found in provided HTML or page — empty result set returned

## How this service works

Level-four headings — Empty value report: Empty value report for Level-four headings. One public HTTPS page or supplied HTML; static parsing, no JavaScript rendering, login or access bypass. Specialised preset in a shared 50-profile, 20-operation engine. 0.01 USDC includes one bounded empty value report result.

## Output

Returns a bounded empty value report identifying which H4 heading elements have empty (blank) values for the specified attribute, parsed statically from a supplied URL or raw HTML without JavaScript rendering or authentication.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "default": "",
   "maxLength": 2048
  },
  "html": {
   "type": "string",
   "default": "<!doctype html><html><head></head><body><h4 id=\"sample\" data-kind=\"example\">Example product guide</h4></body></html>",
   "maxLength": 100000
  },
  "term": {
   "type": "string",
   "default": "product",
   "maxLength": 100,
   "minLength": 1
  },
  "attribute": {
   "type": "string",
   "default": "id",
   "pattern": "^[a-zA-Z][a-zA-Z0-9:_-]{0,49}$",
   "maxLength": 50
  },
  "previous_texts": {
   "type": "array",
   "items": {
    "type": "string",
    "default": "",
    "maxLength": 1000
   },
   "default": [
    "Older example"
   ],
   "maxItems": 200,
   "minItems": 0
  },
  "attribute_value": {
   "type": "string",
   "default": "sample",
   "maxLength": 200
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/h4-empty-attribute-value-report-7da2056d/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from market.datapackvibe.com](https://www.zero.xyz/host/market.datapackvibe.com/llms.txt)