Fri 10/24/25 Update

Never found a definitive solution. 

Suggested Zotero solution doesn't work for me because I rely heaving on my PDF program (Bluebeam Revu) to do markups with toolsets, layers, etc.  Zotero viewer isn't going to have the power I need.

Workaround #1:  Two-step navigation #1.  

• Put PDF link in InfoQube that includes PDF page number.  
• Open the PDF and navigate to correct page.  (input page or number or use bookmark inside PDF)
• Con: Extra steps to navigate to target
• Con: If you rely on page number navigation, the page number references have to be updated when reference file changes.

• Con: If you relay on internal bookmarks in the PDF, these can become difficult to navigate if there are a lot of bookmarks in the file.  

• Conclusion: Page number reference works ok if you're linking to a file that doesn't change (eg a book) but isn't tenable for files that change. 

Workaround #2: Two-step navigation #2.  

• My PDF program DOES have links to individual pages in other pdf's.  
• Create InfoQube link to a pdf "link file" which in turn links to the target destination 

• Con: takes much more time to create links.  

• Conclusion: extra steps to create links are probably too much trouble

Workaround #3: Create individual PDF reference files

• Create a separate PDF file for each individual topic.

• Create InfoQube links to individual topics.

• Conclusion: solves direct link problem but works only on files you create.  Doesn't work for books and articles.

Side note: how do I get the editor to use single-line spacing?  It goes randomly from single-line to double-line and  I can't figure out how to control  it

Wayne

I asked ChatGPT how Revu does it.  Sometimes ChatGPT has useful info (and sometimes not!).  You can delete this post to de-clutter the thread if you want.

Short version: Bluebeam isn’t doing anything “proprietary” here—it’s using standard PDF link annotations and destinations. You can create the same kind of links with any PDF library. Here’s how it works and what to look for if you ever inspect the objects.

How links to pages/places work in PDFs

1) Link = an annotation with an action

• A PDF page has an /Annots array. Each entry can be a /Subtype /Link annotation with:
  • /Rect [x1 y1 x2 y2] → the clickable box (in page user units)
  • /A << … >> → the action to perform when clicked

2) Two key actions

• /GoTo (same document):
  /A << /S /GoTo /D <destination> >>
• /GoToR (other document):
  /A << /S /GoToR /F <file spec> /D <destination> /NewWindow true|false >>
  • /F can be a relative or absolute file spec. Relative paths are common in workflows that keep PDFs together.

3) Destinations (the “place” part)
A destination tells the viewer where and how to display a page. Two flavors:

• Explicit destination array (most precise):
  • [/XYZ left top zoom] → exact coordinates & zoom
  • [/Fit] → whole page
  • [/FitH top] → fit width, scroll to Y
  • [/FitV left] → fit height, scroll to X
  • [/FitR left bottom right top] → fit a rectangle
• Named destination (indirection that survives page reordering):
  • The doc has a Names tree (/Names → /Dests) that maps a string name (e.g., "Page12Top") to an explicit destination.
  • The link then uses /D (name) instead of the array. Viewers resolve the name to the array.

Bluebeam’s “Places,” bookmarks, and hyperlinks typically compile down to either a named destination or an explicit array.

Coordinate system you’re asking about

• Units: PDF user space units (points). 1 point = 1/72 inch.
• Origin: bottom-left of the page’s current user space.
• Transforms: Page rotation (/Rotate) and page boxes (/CropBox, /MediaBox) matter. Annotations are specified in default user space; viewers apply page rotation/crop. If your page is rotated 90°, the annotation rect still uses the unrotated coordinate system—viewers handle it at render time.
• XYZ destination fields:
  • left = X coordinate
  • top = Y coordinate (still measured from the bottom in PDF space; the name “top” is historical—think “set the top edge to this Y”)
  • zoom = e.g., 1.0 for 100%. null (or omitted) means “don’t change current zoom.”

Handy conversion (for scanned pages):
If you know scan DPI and pixel coordinates:
points = pixels * 72 / DPI

Cross-file links (Revu → other PDF)

A typical remote link action looks like:

/A <<
 /S /GoToR
 /F (..\Maps\Sanborn_1911.pdf)
 /D [12 0 R /XYZ 245 612 1.25]   % or a named dest instead of the array
 /NewWindow true
>>

   /F can be a path or a file spec object. Relative paths are best if you move folders around together.

   /D can be an explicit array (like above) or a name (e.g., (Sheet9Corner)).

What Bluebeam adds on top

   Revu’s UI lets you set a hyperlink “Page Only,” “Page with Zoom,” “Snapshot View,” etc. Those map to the /Fit* or /XYZ destination types behind the scenes.

   If you export markups (XFDF), the link regions and targets are described there; when saved back to PDF, they’re standard /Link annotations.

   For resilience, Revu often prefers named destinations for intra-document navigation so links don’t break if pages move.

Programmatic examples (language-agnostic idea + a few concrete snippets)

Conceptual steps (any language / library):

   Open PDF; get target page object.

   Define a destination:

       explicit: PdfExplicitDestination.createXYZ(page, x, y, zoom) (library naming varies)

       or create a named destination and register it in the Names tree.

   On the source page, add a /Link annotation with /Rect and set its /A to /GoTo or /GoToR.

Java (iText 7):

PdfDocument pdf = new PdfDocument(new PdfReader(src), new PdfWriter(dest));
// Destination inside same doc
PdfExplicitDestination dest = PdfExplicitDestination.createXYZ(
   pdf.getPage(5), 245, 612, 1.25f);

// Link annotation rectangle on source page
PdfLinkAnnotation link = new PdfLinkAnnotation(new Rectangle(100, 100, 200, 20));
link.setAction(PdfAction.createGoTo(dest));
pdf.getPage(1).addAnnotation(link);

// Cross-document link
PdfLinkAnnotation ext = new PdfLinkAnnotation(new Rectangle(100, 150, 200, 20));
ext.setAction(PdfAction.createGoToR("Sanborn_1911.pdf",
   PdfExplicitDestination.createFit(pdf.getPage(12))));
pdf.getPage(1).addAnnotation(ext);
pdf.close();

Python (pypdf) – supports internal links; for external GoToR you may need to craft the action dict manually:

from pypdf import PdfReader, PdfWriter
from pypdf.generic import DictionaryObject, NameObject, ArrayObject, NumberObject, FloatObject, TextStringObject

reader = PdfReader("source.pdf")
writer = PdfWriter()
for p in reader.pages:
   writer.add_page(p)

# Build a /GoToR action manually
action = DictionaryObject()
action.update({
   NameObject("/S"): NameObject("/GoToR"),
   NameObject("/F"): TextStringObject("Sanborn_1911.pdf"),
   NameObject("/D"): ArrayObject([
       # destination form: [page_index /XYZ left top zoom]
       NumberObject(11), NameObject("/XYZ"),
       FloatObject(245), FloatObject(612), FloatObject(1.25)
   ]),
   NameObject("/NewWindow"): NameObject("true"),
})

# Add a link annotation on page 1
annot = DictionaryObject()
annot.update({
   NameObject("/Type"): NameObject("/Annot"),
   NameObject("/Subtype"): NameObject("/Link"),
   NameObject("/Rect"): ArrayObject([NumberObject(100), NumberObject(100),
                                     NumberObject(300), NumberObject(120)]),
   NameObject("/A"): action
})
page = writer.pages[0]
if "/Annots" in page:
   page["/Annots"].append(annot)
else:
   page[NameObject("/Annots")] = ArrayObject([annot])

with open("out.pdf", "wb") as f:
   writer.write(f)

JavaScript/TypeScript (pdf-lib) – internal links are straightforward; external GoToR may require low-level object tweaks similar to the Python example.
Practical tips for accuracy (esp. with historical scans)

   Lock zoom with /XYZ for repeatable “view framing”; leave zoom null if you want viewer to keep the user’s current zoom.

   Rotation gotchas: If a page has /Rotate 90, your clickable /Rect still uses the unrotated coordinate system; test after saving.

   Crop vs media box: If you link to a coordinate near the page edge and later change the crop, your “place” can shift visually.

   Prefer named destinations when you expect to reorder pages; let links point to names, and just update the name’s definition once.

   Relative paths for /GoToR so your pack-and-go folders keep working across machines.

If you want to inspect what Revu wrote

Open the PDF with a tool like qpdf or pdftk (dump data) and search for:

   /Subtype /Link

   /A << /S /GoTo or /A << /S /GoToR

   /D [ (explicit dest arrays)

   /Names → /Dests (named destinations)

That will show you the exact coordinates, zoom, and file specs Bluebeam encoded.

If you tell me which direction you want to go (e.g., “I want to generate hundreds of cross-file hotspots from a CSV of coordinates”), I can sketch a small, ready-to-run script in your preferred language that emits /GoToR links using the exact coordinate math you need.