Writing an age is the act of adding symbols representing different features to a Descriptive Book in order to make a customized age. Only very skilled writers will be able to create stable ages that do not fall apart. Players may write any age they would like, though if their writing is not specific enough then things may appear the player did not intend. On the opposite side of the scale, players who write too specifically may introduce conflicts into their ages, which may cancel each other out. Either way, if a balance is not struck, the age will likely be unstable.
To learn symbols, the player will need to place a notebook in the left slot of a writing desk, then place Descriptive Books full of symbols in the right side. All symbols contained in the Descriptive Book will be copied to the Notebook. To get Descriptive Books with unknown symbols in them, players can link to ages that are not fully written. See Missing Symbols.
It is not currently possible to learn symbols directly from another notebook, though players do have the option of adding symbols from one notebook to a blank Descriptive Book and then copying them back out to a new notebook.
To add symbols to a Descriptive Book, the player will need to place one in the right side of a writing desk, with a notebook in the left side. Players may then click on symbols in the notebook to copy them over to the Descriptive Book. Good writers will know which symbols they need, and which symbols they do not. Very good writers will know how to create an age with no internal conflicts, and with no undesired additions.
Currently, Descriptive Books that have been visited cannot have symbols added.
When a player links with an incomplete or even empty Descriptive Book, symbols will be automatically selected in order to create the new age. There are are two types of autoselection, based on the type of symbol missing:
Primary symbols, such as biome controllers, will be autoselected if there are not enough to meet the minimum per category. This will make the age unstable. The minimum number of primary symbols is usually one. Biomes are the exception, the biome controller symbol determines the minimum number of biomes.
Secondary symbols include things like Star Fissures or Mineshafts. These symbols are important to an age's generation, but stable ages may be written without them.
Each individual book will require a different number of secondary symbols per category. When autoselection occurs, if the book does not have any of these symbols, the selector may select symbols to fill these requirements. The selector will never add more than three secondary symbols per category, and never more than five per age. Symbols may belong to more than one category, and there may be symbols that are both primary and secondary.
Primary symbols are required for an age. However, if more than the maximum of each category of symbol is specified, then they will conflict. Only the maximum number of symbols will be used, the rest are ignored, and the age will become more unstable. The maximum number of primary symbols is usually one. Biomes are the exception, the biome controller symbol determines the maximum number of biomes.
Certain symbols will increase instability of an age simply by being used. Dense Ores is one such symbol.