The documents are returned sorted on relevance depending on order, proximity, frequency of terms.
Default search behavior
By default, all search terms are optional. It behaves like an OR logic. Objects that contain the more terms are rated higher in the results and will appear first in their type. For example, wiki forum will find:
- objects that include both terms
- objects that include the term wiki
- objects that include the term forum
Requiring terms
Add a plus sign ( + ) before a term to indicate that the term must appear in results. Example: +wiki forum will find objects containing at least wiki. Objects with both terms and many occurences of the terms will appear first.
Excluding terms
Add a minus sign ( - ) before a term to indicate that the term must not appear in the results. To reduce a term's value without completely excluding it, use a tilde. Example: -wiki forum will find objects that do not contain wiki but contain forum
Grouping terms
Use parenthesis ( ) to group terms into subexpressions. Example: +wiki +(forum blog) will find objects that contain wiki and forum or that contain wiki and blog in any order.
Finding phrases
Use double quotes ( " " ) around a phrase to find terms in the exact order, exactly as typed. Example: "Alex Bell" will not find Bell Alex or Alex G. Bell.
Using wildcards
Add an asterisk ( * ) after a term to find objects that include the root word. For example, run* will find:
- objects that include the term run
- objects that include the term runner
- objects that include the term running
Reducing a term's value
Add a tilde ( ~ ) before a term to reduce its value indicate to the ranking of the results. Objects that contain the term will appear lower than other objects (unlike the minus sign which will completely exclude a term). Example: +wiki ~forum will rate an object with only wiki higher that an object with wiki and forum.
Changing relevance value
Add a less than ( < ) or greater than ( > ) sign before a term to change the term's contribution to the overall relevance value assigned to a object. Example: +wiki +(>forum < blog) will find objects that contain wiki and forum or wiki and blog in any order. wiki forum will be rated higher.
Mission documentation enhancement
The new SAFE standard shall provide specifications for the enhancement of the SAFE documentation so the SAFE control books should briefly describe all the documents that could give a better insight on product generation background (i.e. mission description, sensor description, etc...)
OAIS recommends the implementation of a knowledge network preserving all documentation on the mission and sensor. This could be supported within SAFE by referencing these documents within SAFE. Additionally, it is useful to know for each product type the auxiliary files necessary for its processing to superior levels. So it is proposed to add the following fields in the standard specification:
- References to mission specific documents to implement the knowledge network in OAIS
- List of auxiliary files needed for data processing to obtain superior level product types.
The preservation of the SAFE documentation (fundamental for the complete understanding of SAFE products) shall be carried out with the same care used for products. The preservation format shall be such that it can be read without specific software that is not guaranteed to be maintained in long-term. The preservation of control books should be defined in a format that can be specified using an ASCII-text based schema (e.g. doclet) and using images that can be directly accessed without any pre-elaboration (e.g.bitmap)
SAFE specifications can be produced in the scope of different projects leading to a proliferation of specifications not managed by a centralized authority. A specification configuration control process for the SAFE control book elaboration shall be defined to describe all the steps required for the production, publication and editing of an official SAFE specification authorized by the SAFE management body.