There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "We will import the firenews.csv file that stores a series of web news collected from various RSS feeds."

A block of code is set as follows:

SELECT ROUND(SUM(chp02.proportional_sum(ST_Transform(a.geom,3734), b.geom, b.pop))) AS population 
  FROM nc_walkzone AS a, census_viewpolygon as b
  WHERE ST_Intersects(ST_Transform(a.geom, 3734), b.geom)
  GROUP BY a.id;

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

SELECT ROUND(SUM(chp02.proportional_sum(ST_Transform(a.geom,3734), b.geom, b.pop))) AS population 
  FROM nc_walkzone AS a, census_viewpolygon as b
  WHERE ST_Intersects(ST_Transform(a.geom, 3734), b.geom)
  GROUP BY a.id;

Any command-line input or output is written as follows:

> raster2pgsql -s 4322 -t 100x100 -F -I -C -Y C:\postgis_cookbook\data\chap5\PRISM\us_tmin_2012.*.asc chap5.prism | psql -d postgis_cookbook

Bold: Indicates a new term, an important word, or words that you see onscreen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "Clicking the Next button moves you to the next screen."