By default Draco stores all worksheets in an SQLite-compatible database file. The alternative native Draco format extends the standard OpenDocument Spreadsheet
to store further regression, analysis, textual, and plotting
information. The OpenOffice format is, in reality, a specialized ZIP
file containing a defined set of directories and XML files which store
data, styles, and images. Draco implements these standard files and
directories nominally, but adds Draco-specific XML and data files to the
ZIP file as well. For this reason, Draco can easily export OpenOffice
spreadsheets by simply neglecting to generate the Draco-specific
extensions.
Data
Nominally, data is stored in
content.xml within the OpenOffice file. Draco generates standard
OpenOffice-compliant cntent.xml files, although Draco dates are handled
somewhat differently. Dates are stored as a combination of strings and
values within the file, and a base date and type attributes are assigned
to each date column. The Draco date format is not compatible with
OpenOffice.
Draco does feature an extension, referred to as Quicksave, that stores all numeric data in a
simpler CSV (Comma-Separated Values) file within the OpenOffice file.
The quicksave option allows far more data to be saved and loaded quicker
while consuming considerably less memory. Draco defaults to the
Quicksave format alone for data sets exceeding 250 rows. When Quicksave
is used, the content.xml file will not contain any of the numeric data
from the project.
Analyses
Draco analyses, including basic analyses and regressions, are stored in
an XML file named analysis.xml within the OpenOffice file. This
custom XML file stores all necessary information to nominally
reconstruct analyses and their associated windows. Draco only saves
analyses that were successfully completed; failed or incomplete
regressions and analyses will not be saved to the file.
Regression data saved to the analysis.xml file include the
following:
Regression Type (LS, TSLS, NonLinear, etc.)
Independent Variable
Dependent Variable
Instumental Variables (if applicable)
Fitting Equation (if applicable)
Resulting Parameter Names and Values
Results Text
Covariance Matrix
The data saved from generic analyses (ANOVA, etc.) varies widely between
analysis types.
Plots
Draco saves all plots in a customized plots.xml file. Although
OpenOffice does support saving charts, the XML formatting involved
becomes highly problematic for scatter data without common X-axis
points. Therefore, for reliability and simplicity, Draco uses a
customized, flexible XML format for saving plots.
Because Draco plots are not dynamic, each plot stores all the data
points currently appearing the in chart explicitly instead of refering
to the original data model. Ohter attributes, including axis labels,
legend formatting, and scaling information, are also stored.
Text Windows
All text windows in Draco are saved into texts.xml file
within the OpenOffice container. This file contains a simplisitc format
which simply saves the text and a minimal set of dialog properties.