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Suggestions and Help
The main menu and the initial pages of the historical, publications, and help sections of the site can be reached through the color-coded buttons found at the bottom of every page.


Image illustrating use of the four bottom-of-page buttons to jump to the main sections of the site



Image of hyperlink to an individual report Opening reports
The reports are organized in alphabetical, chronological, and topical lists on the blue publication pages. Open an information page for an individual reports by clicking on its title.

Image of using a hyperlink to download a section of a report Downloading
The information page for each report contains the title, cover, and ordering information about the report. Below that are links to the PDF files for the full report and the individual chapters.

Image of a "Download Link to Disk" popup menu Important:
If you simply click on a link, the file will transfer to a temporary cache file on your computer and you'll be able to read it, but you won't be able to save a permanent copy unless you are using Adobe's commercial product Exchange as your helper application for PDF files. To save a copy of the file on your computer, use your browser's "Save to disk" or similar option. For instance, in Microsoft Internet Explorer, make a pop-up menu appear by clicking on the link and holding the mouse button down (if you are using a Macintosh) or clicking on the link with the right mouse button (Windows and Unix). Choose "Download link to disk..." from the pop-up menu, then choose a location for the file using the dialog box that will appear. Other browsers have a similar feature for downloading files.

Image of the Acrobat toolbar Toolbar
Open the downloaded file using the Acrobat Reader software. (If it has been configured as a helper application for your browser, the Reader may launch automatically.) The controls in the toolbar at the top of the screen are the key to navigating quickly with the OTA documents. Click here for further information about these important controls.

How these documents were prepared
Most of the documents in the OTA Legacy collection were converted from paper to Acrobat® form using an optical character recognition (OCR) process. The reports were scanned, page by page, and then letters and words on the pages were recognized and turned into editable text. Image of an OCR recognition error The OCR process maintains the layout of the original paper pages, including pictures, charts, and other graphics, but it performs poorly on text that is small or indistinct.

When the OCR process fails to recognize a word within a certain confidence level, it places an image of the word on top of its best guess for the recognized text.

The substitutions appear slightly "fuzzy", as in the words "Local Officials" in the image shown here, but they can still be easily read on screen or in a printed copy. Using the Acrobat "Find" command to search for the word "local" would fail to locate it on the page shown here if the best guess (stored invisibly behind the image) is incorrect.

Problems you may encounter
OTA's goal has been to prepare readable, useable electronic versions of its publications within the limits of current technology. The agency's printed reports contain typographical and artistic elements that present substantial challenges for the OCR process, including small fonts, grayscale graphics, and sections of reports printed on shaded backgrounds. As a result, the documents contained at this site are imperfect--but they are readable and useable. The sections that follow explain some of the problems that may be encountered within the documents.

Image of a typical formatting error Formatting & recognition errors
Most of the recognition errors have been corrected within the main body of the documents, but footnotes, captions, sidebars, and other parts of the text still contain such erros as well as others such as improperly assigned fonts, inaccurately applied italics or bolding, and errors in formatting.

Image of a page originally on a gray background Shaded backgrounds
Some of the pages were printed on a gray background that was not amenable to text recognition through OCR. These pages have a speckled appearance and a large number of words replaced by images.


Images of original, onscreen, and printed displays of a grayscale image Indistinct screen display
Many reports contain photographs that were originally printed in shades of gray. The grayscale information could not be preserved; instead, these graphics are stored as high-resolution black and white images. They are displayed onscreen at much lower resolution and may appear blurred or indistinct, but printed versions are more faithful to the original images. (Small white bands may sometimes appear in printed copies.)

Image of a recognition artifact in a map of Texas Artifacts within graphics
Occasionally, the OCR process "recognizes" text where it doesn't really exist, as in this sample where the lower tip of Texas has been converted into a large letter. Most of these errors have been removed, along with other common mistakes such as replacing lines of periods with asterisks or commas in tables of contents.

Recent reports
More recent reports were converted into Acrobat format as part of the normal publishing process. Some of these reports contain a large number of custom fonts embedded within the document. Adobe recommends reserving a memory cache of 50K per font using the ATM® control panel; if garbled text appears within the body of a report, try increasing the size of the ATM font cache.


Tips for Using the Acrobat Reader

 Bookmarks
Image of Acrobat booksmarks If you have downloaded a full report, it will contain hypertext links or bookmarks connected to the beginning of chapters, appendices, and other major sections.

Display format
Image of Acrobat display format buttons The first three toolbar buttons control the display format. Normally, only images of the pages are shown. Choose the middle button to reveal the bookmarks (for full reports). (The button on the right normally reveals thumbnail images alongside the pages, but to reduce download times thumbnails have been included only on the CD-ROM versions of OTA reports and not on the versions available at this website.)

Move and zoom
Image of Acrobat move and zoom buttons Choose the left button (or the scroll bars) to move the page within the window and the magnifying glass buttons to zoom in for a closer look at the pages. The magnification can also be set with the pop-up menu in the lower left corner of the screen.



The fonts used within the documents were originally chosen for readability on printed pages. If they are hard to read on screen, try using a higher magnification or printing the document.

Select and copy text
Image of Acrobat text selection button Choose this button to select text for copying to another application. This tool often selects text or graphics that span more than one column; in many cases, you can constrain the selection to a desired area by holding down the Option key (Macintosh) or Control key (Windows).

Set the page format
Image of Acrobat page format buttons Choose the left button to display a view of the entire page, the middle button to display a full-height view of the page, and the right button to display a full-width view.

Jump to different pages
Image of Acrobat navigation buttons Choose the middle buttons to move forward or back one page, and the end buttons to move to the first or last page of the document. Jump to any page in the document by clicking on the page icon displayed in the lower left corner.
Pages within the document are numbered sequentially. Most OTA reports used separate pagination systems for the front matter and the main body of the text, and in addition many blank pages have been removed from the documents. For these reasons, the Acrobat page numbers do not usually correspond to those listed in the tables of contents within the OTA documents.

Retrace path
Image of Acrobat retrace path buttons Choose the left button to go to the series of last pages visited, and then the right button to return along the same path to the current page.

The OTA LegacyOTA and Congress
OTA PublicationsAbout this disk...