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How to describe maps, site plans and charts in a meeting packet

Give each one two parts: a short alt text that says what the image is, and the information it carries written out in the text nearby. In a packet, that text is often already in the staff report, so the alt text can say where to find it.

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The short answer

The W3C’s Web Accessibility Initiative calls maps, charts and diagrams “complex images”: they hold “substantial information”, more than a short phrase can carry. For those, it says “a two-part text alternative is required”:

  • A short description in the alt text that identifies the image, and says where the details are if they’re elsewhere.
  • A long description: “a textual representation of the essential information conveyed by the image”, in text on the same page or one link away.

The test for the long description is the meeting, not the picture: what would someone need from this image to follow the item and take part?

What to write, image by image

These are our examples, with placeholders in square brackets.

Location map

Alt text: “Location map of [address], the site of item [6]. Described in the staff report.” Long description: where the site is (the street, the nearest cross street, what it borders) and anything the map marks, such as the notice area.

Site plan

Alt text: “Site plan for [project] at [address]. Details below.” Long description: what is proposed, in the order a reader needs it: the buildings and their footprint, parking spaces, driveways and access, setbacks, and anything the board is being asked to approve. If the staff report already has a table of these, point to it rather than repeating it.

Chart or graph

Alt text: what it shows and the main point, for example “Bar chart of [budget] by department, [year]. Details below.” Long description: the data itself, as a table with a header row.

Photo

Alt text: what in the photo matters to the item, for example “The [fence] along the [north] side of [address], leaning and missing two sections.” Most photos need no long description.

A picture of text

A scanned letter, a table pasted as a picture, a flyer: W3C’s advice is to put the text of the image in the alt text, or, if the same text is also present as real text nearby, to leave the alt empty. For more than a few lines, give the text as real text instead.

Scanned pages

A page that is only a picture has no text a screen reader can read. Packets carry them: in the packets we inspected for our research on agenda platforms, a scanned grant application was posted as full-page images with no text, and other attachments had pages that were images only (our research record). Fix it at the source: ask for the original document, or run text recognition (OCR) and have someone check the result against the page.

Decorative images

A border, a background or a logo repeated on every page tells the reader nothing. W3C’s advice for an image that is “purely decorative” is an empty alt attribute, so screen readers skip it. In Word, mark the image as decorative: our Word to tagged PDF guide links Microsoft’s steps.

What a checker can catch

Software can tell that an image has no alt text. It can’t tell whether the alt text says what matters: our guide to what “ADA compliant PDF” can and can’t mean explains the split. In the packets we inspected, one platform had given an image the attachment’s name as its alt text: present, so a checker, Ada Editor included, passes it, but it describes nothing.

Ada Editor flags images with no alt text and alt text that looks like a file name. In English documents it also flags alt text that is a single short word or starts “Image of” or similar, and, when the alt text calls the image a chart, graph, map or diagram, or a site plan, floor plan, plat, elevation or engineering drawing, asks whether it needs a long description. Our list of the checks Ada Editor runs gives the wording of each, and our sorting of WCAG 2.1 AA shows which criteria software can decide in a meeting document.

Corrections and limits

The method is W3C’s; the examples are ours, and what a board needs from a site plan is a judgement the people preparing the packet are best placed to make. This guide isn’t legal advice.

Found something wrong or out of date? Report a correction to this guide (public, on GitHub).

None yet.

Sources

Read on October 12, 2026.