How Experienced Users Avoid Getting Lost in Large Display Networks.
ABSTRACT This article provides a cognitive analysis of how people navigate in the computer medium. As the complexity of computerized information systems increases, interface designers face the formidable challenge of supporting navigation within these systems to allow users to quickly obtain relevant information. Instead of focusing on the comparison of a small subset of proposed techniques for aiding navigation, this study investigates how people handle navigation within the natural context of a familiar computer environment and reveals cognitive processes that can be better supported to aid navigation. The results of a field study and a field experiment converge to support previous navigation-related theories and contribute to a pattern of navigation behavior that has been noticed in domains like anesthesiology and nuclear power. This article describes the characteristics of the computer medium that influence people's ability to navigate, discusses typical navigation problems that arise in this medium, and describes how designers can aid navigation, based on an analysis of how computer users change their behavior and adapt to computer systems to overcome navigation-related problems.
- SourceAvailable from: sigaccess.org[Show abstract] [Hide abstract]
ABSTRACT: A method and tool is presented that extends a word-processor so as to assist with organising personal notes and other information. It is usable by people who are blind or who have low vision, as well as by others, on a small display. The basic principle is to allow the user to annotate parts of the text with labels and then group together any parts of the text that have the same label. The tool was prototyped using the 4DML transformation system, was experimentally evaluated, and refinements are reported on.ACM Sigaccess Accessibility and Computing. 01/2006;
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ABSTRACT: Two alternative interfaces developed for military command and control were evaluated. The theoretical frameworks and concepts used during their development are discussed, and the findings are related to larger issues in display, interface, and system design. Key aspects of cognitive systems engineering (CSE) and ecological interface design (EID) are discussed. An ecological interface was designed with principles of direct perception, direct manipulation, and visual momentum. An experimental version of an existing interface was also developed. An experiment was conducted with a synthetic task environment that incorporated scenarios of tactical operations. Participants were experienced army officers. Dependent variables included status reports for friendly and enemy resources and activities, subjective workload, and information access. Significant results favoring the ecological interface were obtained for six of seven dependent measures. The ecological interface was easy to learn, easy to use, and dramatically more effective than the existing interface. The results are interpreted from the CSE-EID perspective, but insights from naturalistic decision making and situation awareness are also described. The specific design features of the ecological interface are directly applicable to military command and control and similar domains; the overall CSE-EID approach is applicable to interface design for all work domains.Journal of Cognitive Engineering and Decision Making 01/2012; 6(2):165-193.
Article: Visual momentum redux[Show abstract] [Hide abstract]
ABSTRACT: Over 25 years ago Woods (1984) introduced the concept of visual momentum: the extent to which an interface supports a practitioner in transitioning between various information-seeking activities that are required for understanding and exploring work domains. Increasing visual momentum requires the consideration of a range of “cognitive couplings” that span all levels of the interface: between multiple screens, within individual screens, and within a display on a screen. Although the concept has been well received, we believe that its potential to improve the quality of human computer interaction may be under-appreciated. Our purpose in this review is to provide a better understanding of visual momentum: to provide concrete and diverse examples of its successful application, to review empirical findings, to refine and expand the original design techniques that were proposed, and to integrate diverse terms that appear across different research communities.International Journal of Human-Computer Studies 06/2012; 70(6):399–414. · 1.42 Impact Factor
How Experienced Users Avoid Getting Lost
in Large Display Networks
David D. Woods
Cognitive Systems Engineering Laboratory
Ohio State University
This article provides a cognitive analysis of how people navigate in the computer me-
son of a small subset of proposed techniques for aiding navigation, this study investi-
gates how people handle navigation within the natural context of a familiar computer
environment and reveals cognitive processes that can be better supported to aid navi-
been noticed in domains like anesthesiology and nuclear power. This article describes
signers can aid navigation, based on an analysis of how computer users change their
behavior and adapt to computer systems to overcome navigation-related problems.
Increased reliance on computerized systems led many domains to store critical in-
display screen. For example, Electricite de France implemented the first fully com-
INTERNATIONAL JOURNAL OF HUMAN–COMPUTER INTERACTION, 11(4), 269–299
Copyright © 1999, Lawrence Erlbaum Associates, Inc.
Jennifer Watts-Perotti is currently at Eastman Kodak Company, Rochester, NY.
We would like to thank Drs. Phil Smith, Ken Dye, Marshall McClintock, and the Usability Group at
tional Science Foundation (NSF) Graduate Research Fellowship. Any opinions, findings, or recommenda-
Requests for reprints should be sent to Jennifer Watts-Perotti, Eastman Kodak Company, 901
Elmgrove Road, Rochester, NY 14563–5800. E-mail: email@example.com
tegrated patient monitoring system in the anesthesia domain has more than 150
menu screens to allow doctors to access various displays and capabilities (Cook &
Woods, 1996). As the complexity of computerized information systems increases,
interface designers face the formidable challenge of supporting navigation within
these systems so users can quickly obtain information relevant to their tasks and
Many researchers have proposed theories and techniques to aid navigation in
the computer medium (Beard & Walker, 1990; Card, Robertson, & York, 1996;
Furnas & Bederson, 1995; Kahn, 1996; Lamping, Rao, & Pirolli, 1995; Mackinlay,
Robertson, & DeLine, 1996). This article complements the literature by investigat-
ing how people handle navigation within the natural context of an expanded com-
puterized spreadsheet environment.
This article (a) describes the characteristics of the computer medium that influ-
cle focuses on the kinds of information and external cues that allow users to keep
track of where they are in their computer data space, as well as the techniques they
ple navigate in the computer medium will inspire new ways to aid navigation in
thesiology, aviation, and consumer-oriented software.
1.1. Description of the Navigation Phenomenon
Navigation concerns the decisions and actions that contribute to a person’s ability
examine next and call up, move to, or zoom in on other portions of the virtual field
Navigation through large virtual information spaces differs from wayfinding in
physical space because the virtual information space is much larger than the avail-
able viewport of the CRT (see Figure 1). Therefore, computer users may not be able
to view all information relevant to their tasks in parallel. This characteristic is re-
ferred to as the keyhole property (Woods & Watts, 1997).
To study navigation, two studies were conducted to investigate how experi-
the keyhole phenomenon. The first study, a field study, provided the opportunity
to observe experienced expanded spreadsheet users in their natural task environ-
ment. The second study, a more focused field experiment (Woods, 1993b), was a
simulation study, in which experienced spreadsheet users completed tasks
grounded in realistic scenarios. The characteristics of the test spreadsheets for the
field experiment were shaped in ways that should affect navigation, based on the
270 Watts-Perotti and Woods
to new ideas for improving the design of expanded spreadsheets.
The concepts that guided the field study and field experiment came from previ-
ous literature that discussed typical navigation problems, design challenges for
supporting navigation, and possible solutions to navigation problems.
1.2. Typical Navigation Problems
Previous literature indicated that navigation problems encountered in the com-
puter medium include getting lost, display thrashing, increased mental workload,
and underutilization of functionality.
what Woods (1984) called the “getting lost phenomenon” (p. 229). When users be-
the system” (Woods, 1984, p. 233).
An example of the getting lost phenomenon occurred when designers first at-
tempted to convert paper-based instructions for nuclear power plant emergencies
How Users Avoid Getting Lost 271
lowing users to see only a small piece of the information space at one time. Copyright
1991 by Woods & Holloway. Reprinted with permission from the author.
into a computer-based format (Elm & Woods, 1985). To test the system, operators
used the computer-based instructions during a simulation of a power plant emer-
gency. During these preliminary tests,
cide where to go next, or unable even to find places where they knew they should be
In this case, the getting lost phenomenon interrupted the users’ tasks so com-
pletely that they ultimately failed to accomplish their original goals and tasks. It is
important to note that this study ran in a simulated nuclear power plant environ-
ment. The system was never introduced into the field because it would not have
been tolerated in an actual nuclear power plant setting. In fact, most users cannot
afford to become lost in their computer systems. Practitioners in event-driven
worlds like nuclear power or anesthesiology often face time-critical tasks and can-
often necessary for computer users to “bring together two or more pieces of infor-
mation from separated parts of the workspace” (p. 216). If users must serially view
their tasks. The authors noted that in addition to requiring extra time, thrashing
example, they may use file folders and note cards to organize and access informa-
Another common navigation problem in the computer
Mental workload from interface management.
ter navigation problems like display thrashing and getting lost, their workload in-
creases due to the fact that they must concentrate on interface management—how
to travel through or manipulate the interface to find their desired information.
Along with keeping track of their original goals, users must also figure out where
information is located, as well as how to get there in the system. Interface manage-
ment places added demands on resources like memory and attention.
If computer users encoun-
Underutilization of functionality.
ford to get lost or spend time searching for important information within their
ing the ways they work with them (Woods & Watts, 1997). One adaptation is the
Because computer users often cannot af-
272 Watts-Perotti and Woods
1984, p. 234).
ing system in the anesthesia domain. This system combined three kinds of patient
information. Previously, the information was displayed in three separate instru-
ments. However, the new monitoring system integrated the information into a sin-
gle CRT display containing multiple windows and menu-based options. As they
tors must first decide what information they need to see in the system, and then
bring the respective window into view by selecting it from a menu.
erating room, anesthesiologists spent considerable time and effort arranging the
system’s features into a fixed configuration so they could consistently find impor-
tant information within the CRT. This way, the doctors did not have to navigate
through the displays while they were working with patients. Although the new
system introduced new features like the automatic calculation of hemodynamic
values, these features were used only briefly. Eventually, users took advantage of
device flexibility to convert the device to a static, spatially dedicated display (Cook
& Woods, 1996). Therefore, very little of the system’s new features and functional-
ity were ever used.
1.3. Design Challenge: Computerized Information Systems
Should Be Designed to Support Visual Momentum
sual momentum. Woods described visual momentum as a measure of a computer
user’s ability to extract relevant information across views and displays. Many
times, designers focus their attention on creating individual displays in isolation
tegrate information and accomplish their tasks (Woods & Watts, 1997).
When visual momentum is low, users must reorient to the data in each new dis-
play as they travel through the information space. “Each transition to a new dis-
play becomes an act of total replacement; both display content and structure are
independent of previous ‘glances’ into the database” (Woods, 1984, p. 235).
Visual momentum increases with the continuity of structure and content across
different displays. When it is high, the interface mechanisms become transparent
earlier. Some of the techniques to increase visual momentum are display overlap,
longshots, landmarks, and spatial dedication.
switch their attention and reorient to interesting information in their environment
In a natural perceptual field, people easily know when to
How Users Avoid Getting Lost273
(Rabitt, 1984). The coordination of human foveal and peripheral vision often sup-
ports this reorienting process. Peripheral vision provides information about broad
patterns in the surrounding environment and helps people detect sudden changes
their foveal vision, which provides more detailed environmental information.
If designers of computer systems only create discrete detailed displays, they are
not helping users reorient their attention to interesting areas within the informa-
tion space. To help users know when to switch attention, designers can add a cen-
ter-surround-orienting function or focus-plus-context view (Lamping et al., 1995)
normally supported by peripheral vision to the detailed views within their com-
puter systems (Woods & Watts, 1997). Display overlap is one technique that pro-
vides computer users with a better picture of surrounding information than a
narrow viewport normally allows.
technique for supporting navigation in the computer medium (Billingsley, 1982;
Woods, 1984; Woods & Watts, 1997). Longshots provide an overview of the physi-
cal and functional relations among important data within the displays of the infor-
mation space. Effective longshots include a combination of orienting, status sum-
important across-display relations salient, longshots must also be seen in parallel
the detailed views and the longshot.
Providing a longshot of the virtual information space is another
to include landmarks in the virtual information space (Woods, 1984; Woods &
that provide information about location and orientation” (Hochberg & Gellman,
1977, p. 23). Landmarks can be integrated into the computer medium as features
Another way to support navigation in the computer medium is
organizing principle is so compelling that nonspatial data are often given spatial
tion without searching through the entire information space.
Woods (1984) mentioned that “the priority of space as an
1.4. Why Study Navigation in Spreadsheets?
Spatial tools are significant aids to the comprehension of information. Spread-
sheets are examples of this kind of tool. By giving users a system of columns and
274 Watts-Perotti and Woods
rows in which to structure their data, spreadsheets allow users to spatially orga-
nize data that might not be inherently spatial. For example, to keep track of fi-
nancial information over time, people can spatially organize financial figures into
sequential tables that indicate the yearly progress of their financial situation. This
organization allows users to see trends in their data that are not inherent within
the financial figures.
When spreadsheets become too large to fit in one computer screen, their spatial
characteristics continue to support navigation. Even though the entire sheet is not
visible in parallel, it still contains a spatial structure. As users scroll from one area
rate displays. This scanning allows users to develop an internal picture of the to-
pology of the spreadsheet because, as they travel from one area of information to
another, they see the areas that are located between their starting point and their
1.5. The Current Trend in Spreadsheet Design
tial properties, a growing trend in spreadsheet design is beginning to influence the
turism” (p. 172). In an issue of PC World, Scoville and Adams (1993) described the
trend this way:
Over the past several years, spreadsheet programs have evolved into powerful,
broad-based work platforms. In the “anything you can do we can do better” style of
ment. Probably no one routinely uses them all, in fact recent studies have shown that
most people use only a tiny portion of their spreadsheets capabilities. (p. 148)
Included among the dozens of statistical functions is the capability that allows
cated on many different spreadsheets (see Figure 2). This capability offers flexibil-
ity and the potential for users to create spreadsheets containing increasingly
complex information structures hidden behind the narrow computer screen
viewport. Nardi and Miller (1990) found examples of this kind of situation. They
stated that “it is difficult to get a global sense of the structure of the spreadsheet,
which requires tracing the dependencies among the cells. Many users in our study
described awkward pencil and paper procedures for tracing cell dependencies in
debugging spreadsheets” (p. 9).
To address the complexity caused by new features and capabilities, spreadsheet
designers have added more features to support navigation, including “zoom” fea-
tures, which allow users to shrink their spreadsheets to fit into one CRT screen,
“goto” features, which allow users to travel to a specific location within a spread-
sheet, and “find” features, which allow users to find text within their sheets. The
How Users Avoid Getting Lost275
question, then is this: Will the addition of discrete navigation features compensate
for the extra complexity caused by creeping featurism?
The trend to increase features in spreadsheet design has changed modern
spreadsheets into tools that are cognitively different from earlier spreadsheets. As
spreadsheet complexity increases, navigation becomes an important design issue.
Although most people use only a small portion of their spreadsheet’s features
(Scoville & Adams, 1993) the increased flexibility provided by new features intro-
plexity also causes increased mental workload, as users must direct their attention
away from their tasks to find information hidden behind the narrow computer
screen viewport. Therefore, it is the inherent keyhole effect of the computer me-
dium, combined with the increasing size and complexity of spreadsheets, that
makes modern expanded spreadsheets an interesting laboratory for the study of
navigation in the computer medium.
2. STUDIES OF NAVIGATION IN THE COMPUTER MEDIUM
To study navigation, a field study and a field experiment were conducted to dis-
ing multiple links among cells and other spreadsheets (see Figure 2). The partici-
pants for the studies used expanded spreadsheets at work for tasks like keeping
track of college and business-related project expenses, planning yearly budgets for
a college, and creating quarterly reports for government-sponsored projects.
During the field study, experienced users of expanded spreadsheets were inter-
viewed and observed as they completed daily spreadsheet tasks in their normal
276Watts-Perotti and Woods
spreadsheets, which contain multiple links to cells within the active spreadsheet, as
permission from the author.
Modern expanded spreadsheets allow users to link multiple cells and
work environment. Based on the results of the field study, a simulated ex-
panded-spreadsheet environment was designed in which characteristics of test
spreadsheets were manipulated in ways that should affect navigation.
3. FIELD STUDY METHODOLOGY AND PROCEDURES
Field study observations focused on experienced Microsoft Excel users in their
workplace during times when they were working with large spreadsheets. Partici-
pants were interviewed about how they use Excel, and they were observed as they
accomplished their spreadsheet-related tasks for that day.
pants had been using Excel for at least 4 years. Each participant regularly used at
least one expanded spreadsheet that contained between 4 and 50 pages.
ing with their expanded spreadsheets. Each session lasted between 1.5 and 2 hr. At
structured interviews explored how participants use Excel. Finally, participants
accomplish that day. The session ended with follow-up questions asking partici-
During the field study sessions, participants tailored their spreadsheets to sup-
port efficient navigation. Cues that participants used to keep track of their location
were noted, as were strategies they used to reduce the mental workload associated
with navigation. These observations were combined with information from the in-
terviews to create a broader understanding of the cues and strategies people use to
aid navigation in the computer medium.
4. FIELD STUDY RESULTS
4.1. Participants Avoided Navigation
Participants exhibited an overwhelming tendency to avoid navigating in their ex-
panded spreadsheets by placing as much related information as possible into one
How Users Avoid Getting Lost 277
separate areas of the spreadsheet took too much time, especially when they were
comparing numbers located in two different areas of the sheets. Ironically, they in-
vested quite a bit of time and energy before they began their tasks by arranging re-
lated data to appear together in one Excel window.
One way participants avoided navigating in their spreadsheets was by copying
information from one area of the spreadsheet to another. This way, they could eas-
ily compare related data that were initially located in separate areas of the sheet.
the top of a planning area of his sheet. Keeping the copy of the total in this area al-
lowed him to see how it was affected when he changed numbers in the planning
her sheet by keeping a copy of an important summary cell in several areas of her
sheet. She commented that it was frustrating to compare numbers by constantly
flipping among different areas of the spreadsheet. This strategy is a good example
of functional overlap (Woods & Watts, 1997). A third participant avoided navigat-
ing by abbreviating all column contents and using a smaller font so the columns
4.2. Participants Used Landmarks as External Cues to Aid Navigation
The field study demonstrates that people use landmarks like table headings, bold
lines, and elevator or scroll buttons to aid navigation in their expanded spread-
sheets. All participants used table headings to keep track of their surroundings in
bles of detailed data with headings above each table. These headings provided an
at-a-glance summary of the surrounding content of the spreadsheet and therefore
served as landmarks.
At the beginning of each session, participants drew a picture of their spread-
sheet before they opened the electronic version of the sheet. Five of the six partici-
pants included the headings as the only words on their picture, and therefore
appeared to have memorized the relative locations of the headings. When partici-
tour of their sheets. During the tour, they described where they were located in
their spreadsheets by referring to the table headings. They also described the loca-
tion of other areas of the spreadsheet in relation to the area summarized by a spe-
cific heading. Therefore, the table headings not only summarized the area
surrounding them, but also served as frames of reference to help participants es-
tablish their location relative to other areas of the spreadsheet.
The headings contributed so much information to the participants that four of
visible at all times while they scroll through the data in their spreadsheets. These
participants commented that they used this feature to keep from getting lost in
their tables and to make sure they were entering information into their intended
278 Watts-Perotti and Woods
column or row. For example, one participant said that if he did not use the freeze
the functions of the numbers he was analyzing without constantly flipping back to
Table headings in spreadsheets are actually content-laden landmarks because
they provide specific information about the content of the area surrounding them
(Woods & Watts, 1997). This information directly supports users’ tasks and goals
because it gives them precise knowledge of where they are located in their
spreadsheet. For example, a heading called “teachers” indicates that users are
looking at a table containing teachers’ names. In addition to using content-laden
landmarks to aid navigation in their spreadsheets, participants also used con-
tent-free landmarks, which provide only a general idea of where users are lo-
cated in relation to other areas of the spreadsheet. The content-free landmarks
used in this study included bold lines and elevator or scroll buttons (see Figure
3). These landmarks help users know the general area in which they are located,
but users must still search this general area if they are looking for a specific kind
of entry in the spreadsheet.
In the study, 5 of the 7 participants added bold or shaded lines to highlight the
beginning and end of their tables, and all participants bolded or underlined the
and therefore easier to notice as participants scrolled through their spreadsheets.
Four participants mentioned that they used the elevator buttons as a general in-
dicator of their location in their spreadsheet. Elevator buttons appear at the side
and bottom of Excel spreadsheets and allow users to quickly pan across the sheet
(see Figure 3). However, these participants also mentioned that the buttons only
How Users Avoid Getting Lost279
ples of content-free landmarks used by participants. They are content-free because
they only provide a general idea of where users are located in their spreadsheets in-
The bold lines and the position of the elevator or scroll buttons are exam-
helped them travel to a general area of the spreadsheet and did not help them find
specific information within the spreadsheet.
Rather than providing a summary of the area surrounding them, content-free
landmarks like bold lines and elevator buttons provide general physical cues
about where users are located. For example, when users scroll across a large table
and notice a bold, vertical line, they might assume they have reached the end of
4.3. Participants Used the Order of Their Spreadsheets to Keep Track of
Participants who had very large sections in their sheets (i.e., large tables of raw
data, etc.) ordered their sheets in specific ways to help them navigate within each
section. For example, 2 participants were responsible for keeping track of ex-
penses for several projects. Both of them used specific criteria to order their
sheets (i.e., alphabetical order—first by employee name and then by project
name, etc.). This order allowed them to determine where a specific item was lo-
cated within the spreadsheet space (i.e., at the top or in the middle, etc.). Even
though an entry’s physical location changed as more entries were added to a list,
participants could easily find it within an ordered list because its location re-
mained constant in relation to the list.
4.4. Participants Used Paper Copies of Their Spreadsheets to Support
Three participants printed their sheets to check for errors. One participant drew
copies and then used these copies as maps to help them find the errors and make
changes in the electronic version of the spreadsheet.
Not Use Navigation Tools
Participants Tailored Their Sheets to Support Navigation, But Did
Although they might not have been included in Excel’s design specifically for the
participants to modify their spreadsheets to support navigation. Formatting capa-
bilities allowed participants to add landmarks like bold letters and lines to their
spreadsheets, and the ability to sort data into a specific order (like alphabetical and
numerical order) aided navigation by allowing participants to create a fixed struc-
ture in their spreadsheets.
Ironically, tools specifically designed to support navigation were rarely used,
280Watts-Perotti and Woods
sheet on one screen.
• Find, which allows users to find text in the spreadsheet.
5. FIELD EXPERIMENT METHODOLOGY AND PROCEDURES
vided meaningful tasks that were grounded in realistic scenarios for the experi-
ment. The experiment was a simulation study designed to explore ideas gained
sheets were shaped in ways that should affect navigation during the test. The cues
and strategies that were investigated include landmarks, spatial dedication, and
navigation-aiding cues in maps or longshot displays.
The field experiment was a simulation study conducted in a usability laboratory.
Experienced spreadsheet users completed typical expanded-spreadsheet tasks in a
simulated spreadsheet environment. The tasks were grounded in scenarios to in-
the test spreadsheets in ways that should affect navigation. Data included answers
to interview questions, observations of the ways in which participants performed
the tasks, and verbal protocols.
During the experiment, experienced Excel users completed 18 tasks using three
classes of expanded spreadsheets. The classes were (a) landmarks versus no land-
marks, (b) spatial dedication of information versus serial presentation of informa-
emergent properties (see Figure 4). Each class consisted of one spreadsheet that
The experiment included three sheets that explored specific navigation cues.
(One sheet contained landmarks, another contained spatial dedication, and the
lar sheet that did not contain the navigation cue of interest (i.e., one sheet did not
contain landmarks, a second sheet did not contain spatial dedication, and a third
sheet was accompanied by a content-free map). Each condition investigated the
ways in which the presence or absence of navigation cues influenced participants’
The field experiment was a within-subjects design. Each participant completed
tasks with each of the sheets containing navigation cues, as well as tasks with each
of the sheets that did not contain cues. Participants always completed tasks with
How Users Avoid Getting Lost281
the cueless sheet before they interacted with the sheet containing cues. This way,
fore they saw the sheet with landmarks. Therefore, if they added landmarks to the
landmark-less spreadsheet, this behavior would not be influenced by the presence
of the landmarks in the landmarked sheet.
The two spreadsheets in each condition contained similar kinds of information
so that effects due to spreadsheet differences would be minimized. However, be-
cause of the within-subjects design, the details of the information varied within
each sheet to reduce any learning effect that might occur between the two spread-
sheets in each condition.
5.2. Test Conditions
of navigation cue. These test conditions are described next.
Landmarks versus no landmarks.
expanded sheets containing tables of information related to eight different school
Both spreadsheets in this condition were
282Watts-Perotti and Woods
specific navigation cue on participant performance. Participants completed tasks us-
Copyright 1994 by Watts. Reprinted with permission from the author.
each sheet (see Figures 5 and 6).
In the first spreadsheet of this test condition, the tables were separated only by
were therefore forced to find information and conduct tasks without the help of
landmarks. The second spreadsheet contained eight similar tables with different
data. These tables contained table and column headings and lines that separated
How Users Avoid Getting Lost283
bles in the spreadsheet, it is difficult to see where each table begins and ends.
separated by wider lines, and include table and column headings. The combination of
easy to see the borders between tables in the spreadsheet.
Segment of the landmarked spreadsheet. In this spreadsheet, tables are