Tartan carries meaning far beyond most fabrics. Its design elements typically signify the interests or allegiance of the wearer (with the exception of what are often terms ‘fashion tartans’ that are chosen only for their use of colours that are in vogue at the time).
Most older tartans would represent a Scottish clan, or a family, or some other kinship group. (One of the earliest exceptions to this rule was the Clergy tartan, actually designed to protect a preacher from being closely linked with a particular family, to protect from feuding.) But nowadays tartans are designed for events, cities or other geographic entities, military divisions, companies, charities, enthusiasms, churches, schools… in fact practically any form of social organisation.
Tartan designs normally include elements that are meaningful to the client. These inspirations could be references to other tartans (e.g. by basing a new design on a clan or national tartan, whilst adding or modifying individual elements). It is normal to use colours that carry some significance, for historic or personal reasons, or possibly using corporate colours. And numerical elements such as the number of lines or bands can also carry meaning, for almost any reason that is relevant to the social entity being commemorated.
It is normal to use colours that carry some significance, for historic or personal reasons, or possibly using corporate colours. For example, a wedding tartan might include two principal colours to represent the two families being united.
And numerical elements such as the number of threads in a line, or the number of lines or bands can also carry meaning. This could be for almost any reason that is relevant to the people or places being commemorated. One might, for example, choose to use sixteen threads in a band of colour to represent the sixteen nations attending an event for which you are designing a special tartan.