In your post to Acrobat Answers
(http://answers.acrobatusers.com/How-organize-inter-link-tagless-techni cal-PDF-textbook-q19310.aspx)
you mentioned that you do not have the authoring file.
Unfortunate as this means you will have to either manually created links using Acrobat or obtain additional software to work with Acrobat.
(as mentioned in the Acrobat Answers thread)
As to usage of authoring applications and mastering content to get that intelligent/interactive output PDF.
For technical documentation that is of a "living document" nature I find FrameMaker's "Book" feature the most useful.
With that said, depending on this and that one might find InDesign workable.
While Word can be (and is) used for large technical documentation I find it too constraining/limiting as an authoring application.
Fine if I want only hardcopy - too limiting if I want PDF of large technical documents.
(e.g., 20 Chapters of content spanning some 3000 pages)
For chapter, section, sub-section entries (1, 1.1, etc.) the authoring application's Built-In Headings style/paragraph tag must be used.
In FrameMaker, InDesign, and Word these are "unique" and as such support identification of the document's logical hierarchy.
They can become the PDF Bookmarks.
They support the application generation of TOC.
They readily support the graceful creation of inter and intra document links and cross-references.
Similarly, one can master content in FM, InD, or Word such that the "Figure 1.1" title/caption (using built-in paragraph tags/styles) is used.
Any other body text entries that point to "Figure 1.1" can be mastered such that they link to the actual Figure.
The output PDF can reflect this.
But, again, without proper content mastering in an appropriate authoring application the typical recourse is creating the links manually with the Acrobat's Link tool.
Be well...
