Why the standards are necessary
Standards and consistency are necessary to ensure that comparisons can be made by data users about the suitability of data from different sources. This means for example when comparing metadata about property or hazardous waste there is an indication of the dates to which the information refers or if comparing metadata about different map sources the relevant scales are shown. Without this standard meaningful comparisons cannot be made

The standards stated above have different ideas about what characteristics should be included. The FGDC standard for example includes 334 elements but this obviously goes into the detail of the information. To derive all these elements the data provider requires spending considerable time and resources collecting this information and for the data user this detail might be greater than required for an initial investigation. In many situations therefore different levels of metadata need to be defined with the ability to "drill down" into increasing levels of detail. Metadata should therefore vary according to purpose.