Writing (nested) ordered lists in Asciidoctor is easy. We need to start the line with a dot (.) followed by a space and the list item text. The number of dots reflects the levels of nesting. So, with two dots (..), we have a nested list item. By default, each nested level has a separate numbering style. The first level has Arabic numbering, the second lower case has alphanumeric, the third upper case has alphanumeric, the fourth lower case has Roman, and the fifth (which is the maximum depth of nested levels in Asciidoctor) has a style of uppercase Roman.

We can change this by setting a block style for each nested level block. The name of the block style is arabic, loweralpha, upperalpha, lowerromann, or upperroman. With the HTML5 backend, we can also use decimal and lowergreek.

In the following example, we have an ordered list where we set different block styles for the nested level:

= Nested numbering styles

. Services
[arabic]
.. Datastore
.. Mail

. Repositories
// Only HTML backend
[decimal]
.. PostgresDB
.. Redis

. Controllers
// Only HTML backend
[lowergreek]
.. API
.. Admin

. Software systems
// Or use upperalpha for upper case alphanumeric
[loweralpha]
.. OAuth

. Operatings systems
// Or use lowerroman for lower case roman
[upperroman]
.. Linux
[decimal]
... Server A
... Server B
.. macOS
.. Windows server

When we create the HTML output, we have the following result:

Written with Asciidoctor 1.5.4.