California Code, Government Code - GOV § 31511.3

(a) Absence from work or termination of employment while an eligible employee or disability beneficiary, as defined by the long-term disability plan provided by the employer, shall not be considered as breaking the continuity of service.

(b) For the purposes of subdivision (b) of Section 31511.4, an unpaid leave of absence which has been approved by the employer, shall not be considered an interruption of service.  However, the period of time of unpaid leave shall not be considered as service in calculating the retirement benefits otherwise provided under this article.