This is a Test Blog


I originally set up this site to check how newly introduced WordPress.com themes handle both existing images and Gallery display in single Posts, Pages and on archives/categories pages. While one can certainly look at a new theme’s demo site in the WordPress.com Theme Showcase, the demo sites don’t cover all that the Gallery feature has to offer.

Also, please remember that while these Gallery suggestions are valid for both WordPress.com and WordPress.org blogs, self-hosted blogs using the WordPress.org software have far more options than WordPress.com blogs because WordPress.com users do not have access to  the underlying template and PHP files nor can they use plug-ins.

While no further posts are planned, as new themes are regularly being released on WordPress.com and changes to image handling are inevitable, this site will always be a work-in-progress.

Prerequisite reading: Not the Official WordPress.com Gallery FAQ

There is a lot of information here and if you are not familiar with the concepts, perhaps it will not be clear the first time around. Take your time. Bookmark the site. Come back and read it again.

Some points to note:

  1. The Theme currently displayed is shown with only its default settings/options/template. Themes are regularly rotated on this site, but only WordPress.com’s free themes.
  2. Besides the “About” Page, there are four additional Pages on this blog: one Parent Page with a Child Page, one Grandchild Page and one Great Grandchild Page. Not all themes display Page hierarchy in the navigation bar (navbar).
  3. Depending on Theme, you may see additional tabs in the navbar.
  4. Not all themes display a navbar or a Pages widget by default.
  5. No Custom Menu is used here.
  6. The Widgets displayed here (if any) are the theme’s default set of widgets.
  7. There are three Categories in use on this blog: “Uncategorized”, “Gallery” and “Experimental”. No Tags are in use.
  8. Any Post in the “Experimental” category is exactly that. Use with caution.
  9. Unless otherwise noted, all posts use the standard Post Format.
  10. All images appearing in this test blog have been uploaded to and inserted from this blog’s Media Library. Image names reflect the image’s uploaded pixel dimensions. The majority of images uploaded to this test site are at least 600 pixels wide. Some images may not display correctly depending on theme.
  11. When an example of a Gallery shortcode appears in a post, extra spaces have been added around the opening and closing brackets to prevent the Gallery from displaying more than once.

How to use this test blog:
Start by reading the “Hello world!” post and work your way back up from there.

Afterwards, make sure to click on the Parent page to read about displaying new or existing Galleries on Pages and using an HTML table instead of a Gallery.

Commenting is turned off site-wide. If you are a WordPress.com user and still have questions about using the Gallery feature on your blog, please check out the Support forums. If you start a new topic, please tag it with “gallery”, as my RSS reader is set up to alert me to new Gallery threads. This way, we can all learn from the discussion.

If you need to contact me concerning something you’ve seen on this site, or wish to request to reuse information found on this site, please use the contact form on the About page.

An important word about advertising appearing on this site:

Since 2006, WordPress.com has run various types of advertisements on sites hosted with them. These advertisements may include videos and/or photos which are not a part of the posts on this site, although at times they may seem to be. I apologize in advance for any confusion that may arise because of this.

Copyright © 2011-All rights reserved,  Gallery – A Demo Blog

Introducing: Our New, High-Speed Editor

It’s here! WordPress.com completely redesigned the writing experience for its users and along with it a more intuitive way to create Galleries. If you routinely use the default, in-editor Gallery settings, you may find this new method of creating all types of Galleries more responsive, no matter what device you post from. Give it a try!

WordPress.com News


From parents and poets to journalists and politicians, WordPress.com’s publishing tools allow people to make their voices heard.

We have heard your excellent feedback on our interim editor and today, we’re excited to introduce our new editor: a faster, cleaner, and more streamlined way to create posts and pages, and share, promote, and manage content across all your WordPress sites.


Highlights: instant saving, quick sharing

  • It’s fast, responsive, and allows you to create posts and pages quickly on desktop and mobile devices.
  • Easily manage your posts, whether you run an individual blog or wrangle multiple sites, authors, and posts.
  • Access draft posts with one click so that you can iterate and revise quickly when inspiration strikes.
  • Content is automatically saved, allowing you to focus and write — free of distraction.
  • Drag and drop photos, music files, documents, and videos right into your post or page.
  • Tags, categories, and sharing tools…

View original post 95 more words

Welcome to A New Gallery Style: Tiled Columns!

As with the Tiled Mosaic style Gallery, your mileage may vary depending on the number/ratio of portrait to landscape images you include and the theme you are using.

Here’s the same Tiled Columns style Gallery as above, but without the landscape image:

And with fewer images:

Again, like the Tiled Mosaic, you won’t be able to select which images appear larger or smaller or how big or small they appear. It’s all up to the backend programming. As a general rule, the Mosaic Gallery styles will fill the entire width of your theme’s content container. There may also be differences in display between a Gallery which is posted in a Post or on a Page.

All the Points to Consider found in my earlier post “Shapes and Mosaics: New Ways of Displaying Your Gallery Thumbnails” are relevant here as well.

Copyright © 2015-All rights reserved,  Gallery – A Demo Blog

Prerequisite reading:

Image Attachment Pages and The Photo Carousel

Every image you upload to your WordPress.com site creates a corresponding Attachment page. You can check this out yourself by uploading an image directly to your Media Library and then clicking on the “View” link for that image in the Media Library.

When you upload and insert an image via your Post/Page Editor’s “Add Media” button, that image becomes “attached” to that specific post or page. This seems to be the mechanism that allowed the Gallery feature to come about back in 2008 and worked well as long as a Gallery was created only from images uploaded together to the specific post or page where the Gallery was inserted.

Since the Media Workflow update in November 2012, you can also create Galleries from any image in your Media Library irrespective of where the image was uploaded. However, if you do not display your Gallery in the default Photo Carousel, the resulting navigation on image Attachment pages is a nightmare because each Attachment page is attached to the post or page where it was originally uploaded. You can test this now by other-clicking on the above Gallery images and opening the link in a new tab or window (bypassing the default Photo Carousel enabled on this site). The image on the left was uploaded in my previous “One Column Gallery Post,” but nonetheless from that image’s Attachment page you can navigate through all the other images uploaded to that post. The image on the right was uploaded to this post.

The Photo Carousel, which became the default display for all Gallery images almost a year before the Media Workflow update, completely sidesteps this awkward navigation because image display in the Carousel is not dependent on where the image was uploaded. So the introduction of the Photo Carousel was great news for the Gallery feature, not so much for single images.

Beit She'arim Almost Tuscany
Beit She’arim Almost Tuscany

We’ve always been able to insert any image from the Media Library via the Post/Page Editor’s “Add Media” button regardless of where it was uploaded. However, if you choose the “Link to: ‘Attachment Page'” option when inserting it in a post, the corresponding Attachment page is attached to the original post/page where it was uploaded. Click on the image at the right to test this, which will land you in my “Shapes and Mosaics” post and use your browser’s back button to return to this post. The same navigation problem occurs on single images linked to their Media File, which leaves a viewer no option but to hit their browser’s “Back” button to return to your post. (An option available only after inserting the image is to edit the image’s link behavior by checking the relevant box under the Advanced Image Settings>Target which will open the link in a new window.)

It’s not well-known, but you can also display a single image in the Photo Carousel by creating a new Gallery and selecting only that image. To display that image the full width of your theme’s content posting area, you can choose any of the Gallery’s Mosaic types. However, if you want to wrap text around a thumbnail or medium size single Gallery image, you must use the Thumbnail Grid type Gallery, a workaround using the Gallery shortcode with a bit of extra HTML and dip your toes in your Post Editor’s Text tab. Panos explains this well in his post “Shortcode Objects and Changing their Positioning, Part 2“.

This is the same image as above but now inserted as a one-column Gallery using the default Thumbnail Grid style (but modifying the shortcode’s size parameter to display a medium-sized image). Text is wrapped around it just like it is in single image above which was inserted with image alignment set in the Media Handler. Now, however, as long as you have the Photo Carousel enabled by default on your site, clicking on the single image will open the Photo Carousel rather than the image’s Attachment page. Good-bye to awkward navigation and hello light-box style image viewing for all your images.*

In my opinion, even this workaround can quickly become tedious if you are inserting a number of single images in your posts and the same also can be said for having to change each link target for regularly inserted images. What we really need in the Media Handler screen instead of the current choices for inserting images are “Link to:” “None” or “Carousel,” with “Attachment Page” and “Media File” offering an additional check box to open the link in a new window.

As I have said before, image handling on WordPress.com is a continual work-in-progress. There is now a relatively new setting in the Gallery so that images inserted can be linked to “None.” So far this feature works only with the default Thumbnail Grid style of Gallery and only if the Photo Carousel is turned off in your site’s Media Settings. While this is great if you want to have image captions that link to something else, I feel it creates more problems than benefits in the long run, because should you want to use this setting on even a single Gallery, you currently need to give up using the Photo Carousel on your entire site. Adding to that, you will also need to revert to uploading and inserting your Gallery images as was done prior to the Carousel’s introduction to avoid Attachment page navigation problems. A headache, indeed!

*Depending on the theme you are currently using, you may see some differences in border, caption text size and alignment between images inserted regularly and those used in a Gallery.

A grateful hat tip to Panos for his invaluable review and suggestions on this post before and after it went live.

Copyright © 2014-All rights reserved,  Gallery – A Demo Blog

Prerequisite reading:

Media Update: Slideshows Simplified

Any settings in “Link to” or “Columns” are ignored when selecting the Slideshow type option.
Any settings in “Link to” or “Columns” are ignored when selecting the Slideshow type option.

Creating a WordPress Slideshow was entirely re-imagined in the latest update to the Media Manager in November 2012. Gone are the the cumbersome workarounds needed to display only the photos you wanted in the Slideshow and good riddance! To insert a Slideshow in your post or page, you can now use the Media Manager’s options as when creating a Gallery, including removal of selected images from the Slideshow and inserting separate images in the same Post or Page.

After clicking on the “Add Media” button above the toolbar in the Post or Page Editor, click the “Create Gallery” link in the Media Manager’s left sidebar to upload or select the photos you want to include in your Slideshow. Once you’ve made your selections, click the “Create a new gallery” button to be taken to the Media Manager’s Gallery screen. Here you can reorder your images, if needed. Next, in the Media Manager’s right sidebar, choose “Slideshow” from the “Type” box. Lastly, click the “Insert New Gallery” button and the Media Manager will close and a placeholder will appear in the Post/Page Editor’s Visual tab or “type=”slideshow”” will appear in the Gallery shortcode in the Text Editor tab.

This slideshow requires JavaScript.

Adding an entirely separate image to your Post or Page is just as easy as it is in the Gallery.

Hello world!-1024x768

Some points to consider:

  • A Slideshow spans the entire width of your theme’s content posting area and does not link to the Photo Carousel, Attachment page or Media file. As such, the Slideshow sidesteps the current difficulty with image Attachment pages mentioned in my earlier post.
  • The caveat for separate images and image Attachment pages still holds.

Copyright © 2013-All rights reserved,  Gallery – A Demo Blog

Prerequisite reading:

Suggested Further Reading:
Custom Frame Around a WP Slideshow
Uploading and Inserting Images: The Three (Plus One) Link Options

Media Update: Multiple Galleries and Single Images

This post was updated on 28 December 2013

One of the biggest improvements in the November 2012 update to Media Handling is the ability to easily add multiple Galleries and single images in the same Post or Page without the need to manually modify the Gallery shortcode with “includes” or “excludes” as was previously done. This information, however, does not entirely replace my earlier posts on “Gallery with Excluded Image,” “Split Gallery using Includes” and “Include from Media Library Gallery” as the points to consider raised in those posts are still relevant and there are those who may wish to manually configure the Gallery shortcode in order to take advantage of additional sort orders and Gallery image display sizes.

Add a Gallery by first putting your cursor in your Post or Page where you want the Gallery to appear and click the “Add Media” button, then click on the “Create Gallery” link in the Media Manager’s left sidebar. Use the links at the top of the Media Manager to select whether to upload new images from your computer or to select existing images from the Media Library.

If you’ve chosen to upload images from your computer, after your images have finished uploading they will be automatically selected. If you want to include more photos already in your Media Library, you can select them as well.

When you have finished uploading and making all your image selections, click the “Create a new gallery” button, which will open the Media Manager’s Gallery screen. Here you can select each image and add its Title, Caption, Alt Text and Description.

If you want to add more images, click the “Add to Gallery” link in the left sidebar, upload more images or make your selections and then click the “Add to gallery” button and the Media Manager returns to the Gallery screen.

If you want to remove certain images from your Gallery, you can do so by clicking the “x” which appears in the upper right corner of each image when you hover your mouse over the image.

Lastly, in the Gallery screen’s right sidebar, adjust your Gallery settings (link to, columns, type and sort order) and then click the “Insert New Gallery” button. The Media Manager will close and in the Post/Page Editor you will see the Gallery placeholder graphic in the Visual tab or the Gallery shortcode in the Text tab. (Note: the Gallery images themselves will only appear when you Preview your Post or Page.)

Default Gallery layout (Thumbnail grid)

To add a separate image or images in the same Post or Page, place your cursor where you want the image to appear and click the “Add Media” button. Again, use the links at the top of the Media Manager to select whether to upload an image or select an existing image from your Media Library. After you make your image selection and adjust the image settings  in the Media Manager’s right sidebar for Title, Caption, Alt text, Description and Attachment Display Settings (alignment, link to and size), click the “Insert into Post” button.  The Media Manager will close and your image will appear in the Post Editor.

It’s that simple and works for creating and inserting multiple Galleries as well! Just repeat the process for inserting a Gallery and, of course, each Gallery can have its own settings.

Type: Tiles

For those that would like a visual explanation, a video!

Some points to consider:

  • All the caveats on using image Attachment pages pointed out in my earlier posts on this site and in my Gallery FAQ have become acute now that it’s possible to create a Gallery using previously uploaded images from the Media Library. Currently there is no ability to navigate between those image Attachment pages in an orderly manner as there is when uploading and inserting images together in a Gallery. When using existing images from your Media Library in a Gallery, each image Attachment page opens and points to the post where it was originally uploaded. As far as I know, the only way to assure consistent browsing between Gallery images is to display your Gallery images using only the Photo Carousel.
  • This caveat is also true for single images that have been linked to their Attachment page.
  • The Gallery “types” (Square Tiles, Tiled Mosaic, Circle) have had some unexpected display behaviors when the browser window is resized or when viewing on tablets or mobile devices. To test this in your theme, resize your Post or Page preview window and, if it happens, please take a moment and post in the Themes forum stating what theme you are using and what Gallery type you’ve used.

Copyright © 2012-All rights reserved,  Gallery – A Demo Blog

Prerequisite reading:

Shapes and Mosaics: New Ways of Displaying Your Gallery Thumbnails

This post was updated on 3 September 2015

WordPress.com has recently introduced some interesting new ways for its users to display their Galleries.

Shapes: In addition to the Gallery’s default Thumbnail Grid, which takes its shape from your uploaded images (i.e. portrait or landscape), you can now display your Gallery thumbnails as Circle, Square Tiles or Tiled Mosaics.  If you’ve uploaded irregularly sized photos in your Gallery, this will even out the display of those images.

The “type” parameter can be applied on a Gallery-to-Gallery basis and can be added to the Gallery from the dropdown menu in the Gallery Screen of the Media Handler or by directly modifying the Gallery shortcode in the Text tab of the Post or Page Editor.

In the Media Handler, choosing “Circles” (or in the gallery shortcode: [ gallery type=”circle” ]) will cause your Gallery thumbnails to display like this:

Choosing “Square Tiles” in the Media Handler (or shortcode [ gallery type=”square” ]) will make your thumbnails display like this:

and lastly, choosing “Tiled Mosaic” (or [ gallery type=”rectangular” ] although Staff has indicated that type=”rectangle” also works), like this:

Setting Tiled Mosaic as Default: You will find this under Dashboard>Settings>Media>Image Gallery Carousel>Tiled Galleries> Display all your gallery pictures in a cool mosaic. This setting will change the default display of all Galleries globally on your site so that they appear as a tiled mosaic (like the one shown just above) rather than as individual thumbnail images. It is not currently possible to set which images display larger or smaller than the others.

Regardless of which thumbnail display option you choose, there is no change to how images appear when viewed individually, whether in the default Photo Carousel, the image Attachment page or the Media File.

Some points to consider:

  • The “size” parameter does not function when the Mosaic types are used. Gallery thumbnails are resized dynamically to fill the entire width of your theme’s content column.
  • For the “square” and “circle” thumbnail display, images are best uploaded in multiples of three. Otherwise, you may see odd image sizing to compensate for the width of your theme’s content column. In the sample Galleries above I’ve deliberately used 5 images to demonstrate this. When I used 4 images, the “leftover” single image filled the entire width of the posting area.
  • Both the “square” and “circle” mosaic type do now accept the “columns” parameter, but in order to use it, you will need to manually edit the Gallery shortcode in the Editor’s Text tab.
  • Image Captions: If you use captions extensively on your images, you may find that the new Gallery types truncate them or do not display them at all. Keep in mind that this only affects the front page and single post display. Once a Gallery image is clicked, the caption is visible in the Photo Carousel or Attachment Page.
  • If you find that on your theme these new Gallery options display unexpectedly, won’t you please take a moment to post in the Community Themes Forum and let us know which theme you are using and which Gallery “type” you’ve used. That way we can let the Theme Team know if a theme needs fixing.

Copyright © 2012-All rights reserved,  Gallery – A Demo Blog

Prerequisite reading:

Using A Single Image as a Gallery Portal

This post was updated on 8 August 2014

Perhaps you’d like to have a single image act as a focal point for your writing but still be able to display more images without having to insert an entire Gallery’s worth of photos in your Post. Even at thumbnail size, having many images can potentially overwhelm your written content. You could, of course, use a Slideshow instead of a Gallery. However, in its present form the Slideshow spans the full width of your theme’s content area which can be distracting as well.

So how can you make a single image act as an entry to a gallery of images? It’s simple, but it also has some serious limitations compared to the usual way of creating a Gallery.

Click the Above Image to See More

The “Why” and the “How”: When you upload your images together to a single post or page, they become attached to that post or page. You can use this characteristic to create a portal while still only inserting a single image in your post.

To create your focal point image, click the “Add Media” button and upload all your images together to the post or page where they are to appear. After uploading the Media Handler will automatically select all the images you just uploaded. Uncheck everything except the first image uploaded that will be used as the gallery portal image. Insert that image in your post as a regular image and in the “Attachment Display Settings: Link to” field select “Attachment Page.” Now clicking on that image in your Post will take your visitor to the Attachment page and they can then browse all the images uploaded using the previous and next buttons there.

Some points to consider:

  • Not all themes, especially WPcom’s newer themes, include navigation links on Attachment Pages. In order to use this “focal point” technique, test first that the theme you are using does include them.
  • Before you upload your image files, you will want to name them in a way that they will then later display the Attachment pages in the order you want them to appear.  In my example I’ve given all my image files the same name (galleryportal), but have appended each name with a number, 01-04. Once uploaded, the image Title field of each image will automatically be filled in with the same name as the image file itself. You can later change the image Title field to something more suitable and, regardless, the file name itself will remain the same as when uploaded and the display order maintained.
  • It is essential that the images used to create this portal are uploaded together in the Post or Page where you wish them to appear.
  • Rearranging images in the Media Handler window after upload does not change the order of Attachment page display.
  • The Photo Carousel will not display when using this technique.
  • Every image uploaded in the Post or Page is displayed in the portal, unless you delete the image from the Media Library.

Copyright © 2012-All rights reserved,  Gallery – A Demo Blog

Prerequisite reading:

Gallery as an Index Page

This post was updated on 28 February 2014

What follows is a workaround to link Gallery images to Pages and or Posts or external URLs. While this workaround does work, read on to understand its limitations.
For about a year and a half there was a very active thread in the WordPress.com Community Ideas Forum requesting a change to how the Gallery feature functions so that this workaround becomes unnecessary. Regretfully, that thread finally closed to new posts in July 2015 without resolution.

It has been possible to add clickable links in the Description area of images for quite some time, but starting from around May or June this year this function was extended to image Captions as well. This subtle addition allows the Gallery feature to be used as an Index page or portal for other information, with some limitations (see “Some points to consider” below).

There are two ways you can add Image Captions and/or Descriptions once you’ve uploaded your images:

  1. Via the post/page itself, by clicking on the Gallery placeholder in the Visual Tab of the Post/Page Editor and then on the Edit Gallery icon that appears in the upper left corner of the Gallery, which will then open the Media Handler’s Gallery screen, or
  2. Directly in the Media Library, after clicking the Edit link that appears under each image in the Media Library

Adding links in image descriptions or captions is not as simple as creating links via the “insert link” function in the Visual tab of the Post/Page Editor of posts or pages because the links must be added as HTML code. Thankfully, for those of us who are HTML challenged, it is possible to create the links in a draft post or page’s Visual tab and once the link is created, by switching to the Text tab to copy and paste the resulting HTML code into the image caption or description area. Tip: Keep two tabs or browser windows open to make this easier. If you are comfortable writing HTML, you can, of course, add these links directly after upload. In all cases, make sure to click “Update Gallery” when done to close the Media Handler.

As a Gallery can only display images, I’ve used various sizes of icons in my above example Gallery so you can see this theme’s spacing and alignment in the Gallery’s default Thumbnail Grid (which, using columns, gives more control over placement of the icons), but you can also use thumbnails of documents or any other image to represent the link.

It is also possible to create a similar portal using an HTML table, as explained in “When is a gallery not a Gallery“.

Some points to consider:

  • This technique works best with the Gallery’s default Thumbnail Grid rather than with Gallery types and assumes that you are creating your Gallery either in a Page or in a Post using the Standard post format. This technique may have unexpected results on any Post using the Gallery post format. (More about Post Formats.)
  • When a visitor clicks on the Gallery’s thumbnail image rather than the caption, the Photo Carousel or image Attachment page or the image itself will open. If you’ve turned off the Photo Carousel under Settings>Media>Image Carousel, you should set the Gallery to link to the  Attachment page so that visitors can still click on the link in the caption or description that appears there.
  • The tendency of visitors to click the icon is the obvious disadvantage of using the Gallery in this way. Most people will click on the icon rather than the caption, so give them every opportunity to reach the link.
  • The Gallery feature is designed to ignore any link inserted in an image’s Custom URL field.
  • Links added to captions or descriptions can be external links, other Pages, Posts, PDF documents, or any other file type supported by WordPress.com. (See also, Uploading Documents.) On the last icon above, I’ve labeled each field as it appears in the image settings window.
  • Captions should be short. Lengthy captions may distort image alignment.
  • Gallery Thumbnail and Caption alignment may differ from what you see here depending on the theme you are using.

Copyright © 2012-All rights reserved,  Gallery – A Demo Blog

Prerequisite reading:

Suggested Further Reading:

If you want to learn more about using HTML, here are a few guides to get you started:

New lightbox style “Photo Carousel” comes to the Gallery feature

Today WordPress.com implemented a new Photo Carousel on all posts using the Gallery feature, including existing Galleries.

Without a doubt, a “lightbox” style image viewer has been one of the most hotly requested features here on WordPress.com. However, for those of us who have used the Gallery’s image attachment page to give extra information about the photo, drawing, sketch, etc. (think travelogue, portfolio, etc.), all of that information is currently invisible to the viewer.

In June and July 2012 the Photo Carousel was updated to include the following:

  • The image’s caption, title and description
  • A Reblog icon
  • A link to the full size image, which opens in a separate window
  • If commenting is enabled, the ability to comment directly in the Photo Carousel
  • Optional display of EXIF data (if present in the uploaded image)
  • The ability to change the Photo Carousel’s default black background to a white background.

Displaying images in the Photo Carousel is the current default behavior for the Gallery feature and images are dynamically re-sized to fit the viewer’s browser screen size.

If you want to disable the Photo Carousel completely for your site and revert to the Gallery’s original function of either displaying a larger image or an image attachment page after clicking on a Gallery thumbnail, or adjust the Carousel’s settings, you can now do this in your Dashboard>Settings>Media>Image Gallery Carousel.

Copyright © 2011-All rights reserved,  Gallery – A Demo Blog

Prerequisite reading:

Gallery As Custom Excerpt

Bacon ipsum dolor sit amet swine pork chop beef t-bone ball tip capicola ham hock, corned beef jowl. Boudin tongue rump meatball brisket cow, swine prosciutto ball tip. Pork belly shankle t-bone turducken, kielbasa short loin shank bacon filet mignon turkey. Pastrami ground round shankle, boudin beef flank pork tongue shank rump sausage. Venison tri-tip ground round, bresaola ham hock pastrami drumstick tail pork loin pancetta meatloaf shank ham swine andouille. Spare ribs pork belly tongue tenderloin. Beef ribs ribeye cow ham brisket short loin.

(This filler text courtesy of Bacon Ipsum .)

And the real point of this post can only be seen on the front page of this blog. If you cannot see the Custom Excerpt using the Gallery post format,  based on this reference post on wpbtips, it means that the theme presently being displayed does not support the Gallery post format and/or the use of Excerpts.